72 3/4 Ton 4x4 Truck Questions - Please Help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

unixadm · 06-12-2005, 07:35 PM

Hello,

I recently purchased a 72 C20 3/4 Ton Truck. It was a local purchase, pretty clean and the price was $2500. It's a 4x4 which was a plus, but not required. Well after I did some research, this truck appears to be a 2wd to 4wd conversion. That does not bother me, but something isn't quite right under the front end. It has a D44 8lug up front, SM465, NP205, 350 4bbl, and a Dana 60 No-Spin in the rear with leafs. It looks like whom ever did the conversion got parts from a donor vehicle, but either didn't install the right parts, didn't get all of them, or was just an idiot.

First off, if anyone has a 71-72 4x4 350 manual, I'd really appreciate it if you could snap some pictures from above and below of the engine mounts and the transmission cross member locations.

The motor is sitting far forward. It has a high hump floor installed, but I believe it was an automatic high-hump that they modified. The transmission pokes through where the high hump starts to go upwards towards the firewall. The whole thing looks like it's 2" too far forward, but I'm new to these trucks and have no idea.

The problems I noticed is that the Dana 44 pumpkin has hit the passenger side engine tower/mount. The engine mount is broken right now and there are signs of rubbing. However no rubber bumpers are installed, so that 'could' be the problem. There is only about 1.25 to maybe 2" of clearance between the pumpkin and the engine mount. That is why I'd like some pictures so that I can compare.

The other areas I noticed is the kludged front swaybar frame mounts, the missing fan shroud (I bought what I thought was the correct NOS one, but it's too deep), and a few other things. There are mounting holes on the frame that looks like things can be placed at different positions. The bottom line is - If the thing isn't right I'm not going to fix it right now. I'll put some bump stops on the front, fix the motor mount and drive it. However down the road I want to convert back to the a Th350 or TH400 or some automatic with a NP205.

So if anyone can help me out and tell me one way I'd appreciate it. I got a several cross members with the truck, most likely the original 2wd pieces. With some pictures hopefully I can solve this mystery.

I'm betting the truck originally had 4 wheel drums, but now it's fitted with 8lug discs up front which is nice.

Thanks!!!!

nu2-72 · 06-12-2005, 07:44 PM

First, is the title 71 up? Then it would have had discs up front either 2wd or 4wd.
I have both auto and 4 speed 72's. It is getting late here but I can get some pics tomorrow for you if no one else gets some first.
2wd big block trucks had high humps and all 4wd. If it is a conversion, was the cab changed, and/or just suspension and were the titles married? You don't have to answer these if you do not want to. They are just questions that come up when this kind of thing happens. Some people do not want to tell.
There is lots of info here and welcome to the board.

stelth2002 · 06-12-2005, 07:46 PM

If you look on the frame there are 2 spots where the towers can bolt to. Yours is probably in the front. This is why your entire drivetrain is being to far foward. That adds to the problem that your pumpkin on the diff is hitting the crossmember. Sounds like you have quite a project. The best thing to do would be to probably move the entire drivetrain back, but that would be quite an effort unless you had lots of jacks and could manage to drill all the holes needed in the right spots. Being that its a 72 it should have came with discs from the factory. The factory hump should have a rolled smooth edge where the shifter comes thru. My 6 clyinder originally had a hump that sounds like yours. But that seems like a whole different case.

I also sent you a PM about the wheel.

JT

unixadm · 06-12-2005, 08:11 PM

Thanks guys. Please keep the responses coming. Pictures will really help me.

I do have several jacks, and an engine hoist. The exhaust is junk so I don't mind sending it to the work dumpster. If I do move the drivetrain back then I would switch it to an automatic at the same time. Pulling the motor in this thing looks pretty easy.

Basically I want to make sure the correct front cross member is installed. I'm also wondering how the clutch linkage is working. Why would they have moved the drivetrain so far forward to begin with? Ugh. I would also need to worry about the driveshafts no longer working. Everything in this truck looks 'old'.

This is not the end of the world - the truck drives okay as it stands today. But I'm a stickler for having things done the right way. I may try to hunt down a newer drivetrain and do a full swap.

unixadm · 06-12-2005, 09:32 PM

You can see some pictures here:

http://www.dmwtech.com/gallery/v/k20/4wd/

You may have to scroll down to see the pictures after clicking. For some reason, IE does not work correctly with Gallery 2. Firefox works fine though.

knsmodels · 06-12-2005, 10:15 PM

unix.....here are pics of my 1/2 ton 4X4....you are in luck as I have the inner fender off and I was able to get some good pics of side of engine....hope these help....all 4X4's have the straight down exit rams horn exhaust manifolds which I notice yours does not and they probably would not work on yours either as it does look like your engine is to far forward....Good luck...Paul K

PS let me know if you need other pics.

unixadm · 06-12-2005, 10:25 PM

Perfect. Thank you very much.

Yeah that confirms it. Mine has the angled ram horn manifolds - but replacing them isn't a big deal. I'll get the brakes done up so that I can haul some stuff and in the fall, I'll pull the drivetrain and make things right. I only need to determine if the engine cross member I have is correct. Right now, it does not have a cross member installed, just some stand offs that bolt to the frame.

At least most of the parts are there - I just need to make it right.

**JIMs70GMC** · 06-13-2005, 06:34 AM

Sounds like you have a 2wd frame. Their should be holes for the I6 position all ready in the frame that's where you'd want to put the correct cross member.

unixadm · 06-13-2005, 06:33 PM

Yeah - I see extra holes and it is a 2wd frame. Is the top cross member in the attached picture the correct one?

*72longbed* · 06-13-2005, 07:19 PM

Top crossmember appears to be the correct 4x4 application. Nows the time to think about how close you want that distributor to the firewall. If you go with the stock 4x4 engine cradle location and you want to run an HEI, it will be very close to the firewall. I'll be moving mine so that the rear of the HEI is about 1.5" away from the firewall.

Good luck with the fix,
72longbed

drink2mny · 06-14-2005, 12:40 AM

Could it be that his motor is that far up because...it is a 2 wheel drive frame and are setup a little different than a 4wd frame??

drink2mny · 06-15-2005, 01:07 PM

I would keep the motor and driveline where it is at, and put the crossmember in and put 2" of lift on her and call it good...

Otherwise you will be heading into headache land, with moving everything back..

Mudder · 06-15-2005, 02:11 PM

Ya wanna make sure you can still get your dizzy out if you move things back.

unixadm · 06-24-2005, 03:56 PM

Guys - I removed the motor mount bolts and jacked the engine up. I have a bad motor mount on the passenger side that needs replacing. I grabbed the cross member that's in the photo above (top crossmember), however after measuring the inside of my frame rails (about 27 3/4", the cross member is up to 29" wide. So I'm wondering if this isn't a 73 or newer cross member. I have two cross members and 1 set of engine mount arms. It does look like going with the cross member would help some of my clearance issues - but I won't be sure until it's bolted in.

I'm wondering if I can't shorten it up, drill some new holes and get it to fit. I guess the only thing I can waste is time.

If anyone has a front 4x4 engine cross member for sale, please let me know.

*72longbed* · 06-24-2005, 06:46 PM

I would never suggest moving things back?!?!? Where did that come from?? The only possible way that the driveline on a 67-72 4x4 could go is slightly forward. The crossmembers will both slide forward between the frame rails with no problem, and there are even a couple of bolt holes in the front frame rails from the factory that could be used. Going forward with the driveline, will bring the distributor AWAY FROM THE FIREWALL.

Common sense,
72longbed

unixadm · 06-24-2005, 07:48 PM

72longbed -

I'm going to leave the engine and drivetrain where it's at. The drivelines and everything else are working, so the only real reason for moving it that I saw was:

1. Clearance between the engine towers and the front diff pumpkin
2. Make the truck factory 4x4 correct

After sliding in the second 4x4 cross member that I have backwards, it would appear that I'll have more clearance.

The engine towers that are in the truck right now look half factory and half home made. Both of the towers have significant cracks in them. While I could weld them back up, there was obviously a flaw in the persons thinking who did the initial work.

The 4x4 cross member that I have isn't the right one. However with some cutting and grinding, plus a little welding to fill in the old bolt holes I should be able to make it work. I'll get it to fit where I need it, lower the engine, install the cross member to motor mount bolts, make sure it's square and then drill 4 holes on each side and fasten with grade 8 hardware. I'm only learning how to weld and fabricate, but by holding up the home brewed mounts that were in there to this 4x4 cross member, the engine mount pads seem to line up which is a good thing.

Hopefully I can knock this out tomorrow. I did get all of the hack job mounts out and bolted on two new motor mounts to the engine. All of the bolts were finger tight if that and one motor mount bolt was missing on the passenger side. Sweet. The motor must have been shifting around like crazy as not a single bolt was tight anywhere. I think there was a lot of beer in garage fridge during those weeks or months that this truck was being converted to 4wd.

unixadm · 06-25-2005, 03:03 PM

Well I modified/shortened the cross member I had and was able to get it installed. Then I realized I put the damn thing in backwards so I had to take it out and swap it around. Duh.

Considering this isn't the right cross member, it fit pretty well. I still need to drill the holes in the frame to mount it, but the engine is bolted to it with no issues.

I did gain some clearance between the pumkin and the cross member, but not a whole lot. I'm hoping with the bump stops installed it won't hit. If it does, I'll just either take it very easy or put a 2-4" lift on the truck. At least the cross member is a lot more sturdy than those home made engine mount brackets that were on the truck! I'll get some pictures so you guys can see what I'm talking about.

06-12-2005, 07:35 PM	#1
unixadm Registered User Join Date: Jun 2005 Location: Sacramento, CA Posts: 61	72 3/4 Ton 4x4 Truck Questions - Please Help Hello, I recently purchased a 72 C20 3/4 Ton Truck. It was a local purchase, pretty clean and the price was $2500. It's a 4x4 which was a plus, but not required. Well after I did some research, this truck appears to be a 2wd to 4wd conversion. That does not bother me, but something isn't quite right under the front end. It has a D44 8lug up front, SM465, NP205, 350 4bbl, and a Dana 60 No-Spin in the rear with leafs. It looks like whom ever did the conversion got parts from a donor vehicle, but either didn't install the right parts, didn't get all of them, or was just an idiot. First off, if anyone has a 71-72 4x4 350 manual, I'd really appreciate it if you could snap some pictures from above and below of the engine mounts and the transmission cross member locations. The motor is sitting far forward. It has a high hump floor installed, but I believe it was an automatic high-hump that they modified. The transmission pokes through where the high hump starts to go upwards towards the firewall. The whole thing looks like it's 2" too far forward, but I'm new to these trucks and have no idea. The problems I noticed is that the Dana 44 pumpkin has hit the passenger side engine tower/mount. The engine mount is broken right now and there are signs of rubbing. However no rubber bumpers are installed, so that 'could' be the problem. There is only about 1.25 to maybe 2" of clearance between the pumpkin and the engine mount. That is why I'd like some pictures so that I can compare. The other areas I noticed is the kludged front swaybar frame mounts, the missing fan shroud (I bought what I thought was the correct NOS one, but it's too deep), and a few other things. There are mounting holes on the frame that looks like things can be placed at different positions. The bottom line is - If the thing isn't right I'm not going to fix it right now. I'll put some bump stops on the front, fix the motor mount and drive it. However down the road I want to convert back to the a Th350 or TH400 or some automatic with a NP205. So if anyone can help me out and tell me one way I'd appreciate it. I got a several cross members with the truck, most likely the original 2wd pieces. With some pictures hopefully I can solve this mystery. I'm betting the truck originally had 4 wheel drums, but now it's fitted with 8lug discs up front which is nice. Thanks!!!! Last edited by unixadm; 06-12-2005 at 07:37 PM.

06-12-2005, 07:44 PM	#2
nu2-72 Senior Member Join Date: Apr 2001 Location: Amazonia, Mo. USA Posts: 2,821	First, is the title 71 up? Then it would have had discs up front either 2wd or 4wd. I have both auto and 4 speed 72's. It is getting late here but I can get some pics tomorrow for you if no one else gets some first. 2wd big block trucks had high humps and all 4wd. If it is a conversion, was the cab changed, and/or just suspension and were the titles married? You don't have to answer these if you do not want to. They are just questions that come up when this kind of thing happens. Some people do not want to tell. There is lots of info here and welcome to the board. __________________ 72 3/4 4x4 350 4spd 72 3/4 4x4 350 auto 2004 Duramax Silverado 4x4 2006 Duramax Crew cab 4x4 2010 Harley Ultra Limited 2011 Harley Street Glide

06-12-2005, 07:46 PM	#3
stelth2002 Young Gun wth Fast Inline Join Date: Jan 2002 Location: Idaho Posts: 1,475	If you look on the frame there are 2 spots where the towers can bolt to. Yours is probably in the front. This is why your entire drivetrain is being to far foward. That adds to the problem that your pumpkin on the diff is hitting the crossmember. Sounds like you have quite a project. The best thing to do would be to probably move the entire drivetrain back, but that would be quite an effort unless you had lots of jacks and could manage to drill all the holes needed in the right spots. Being that its a 72 it should have came with discs from the factory. The factory hump should have a rolled smooth edge where the shifter comes thru. My 6 clyinder originally had a hump that sounds like yours. But that seems like a whole different case. I also sent you a PM about the wheel. JT __________________ 1967 Chevrolet LWB with built 292! 415 ft. lbs of torque, 4 speed :O with 27% overdrive too, 3.73 Posi. Frame and body done... getting painted!!!

06-12-2005, 10:15 PM	#6
knsmodels I make Models Join Date: May 2005 Location: Bucks, PA Posts: 626	unix.....here are pics of my 1/2 ton 4X4....you are in luck as I have the inner fender off and I was able to get some good pics of side of engine....hope these help....all 4X4's have the straight down exit rams horn exhaust manifolds which I notice yours does not and they probably would not work on yours either as it does look like your engine is to far forward....Good luck...Paul K PS let me know if you need other pics. __________________ Click to see what I do 1972 LWB K10 350/4 sp 1968 SS Chevelle 396/tremac5spd

06-13-2005, 06:34 AM	#8
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	Sounds like you have a 2wd frame. Their should be holes for the I6 position all ready in the frame that's where you'd want to put the correct cross member. __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm Last edited by JIMs70GMC; 06-13-2005 at 06:35 AM.

06-12-2005, 08:11 PM	#4
unixadm Registered User Join Date: Jun 2005 Location: Sacramento, CA Posts: 61	Thanks guys. Please keep the responses coming. Pictures will really help me. I do have several jacks, and an engine hoist. The exhaust is junk so I don't mind sending it to the work dumpster. If I do move the drivetrain back then I would switch it to an automatic at the same time. Pulling the motor in this thing looks pretty easy. Basically I want to make sure the correct front cross member is installed. I'm also wondering how the clutch linkage is working. Why would they have moved the drivetrain so far forward to begin with? Ugh. I would also need to worry about the driveshafts no longer working. Everything in this truck looks 'old'. This is not the end of the world - the truck drives okay as it stands today. But I'm a stickler for having things done the right way. I may try to hunt down a newer drivetrain and do a full swap.

06-12-2005, 09:32 PM	#5
unixadm Registered User Join Date: Jun 2005 Location: Sacramento, CA Posts: 61	You can see some pictures here: http://www.dmwtech.com/gallery/v/k20/4wd/ You may have to scroll down to see the pictures after clicking. For some reason, IE does not work correctly with Gallery 2. Firefox works fine though.

06-12-2005, 10:25 PM	#7
unixadm Registered User Join Date: Jun 2005 Location: Sacramento, CA Posts: 61	Perfect. Thank you very much. Yeah that confirms it. Mine has the angled ram horn manifolds - but replacing them isn't a big deal. I'll get the brakes done up so that I can haul some stuff and in the fall, I'll pull the drivetrain and make things right. I only need to determine if the engine cross member I have is correct. Right now, it does not have a cross member installed, just some stand offs that bolt to the frame. At least most of the parts are there - I just need to make it right.

06-13-2005, 06:33 PM	#9
unixadm Registered User Join Date: Jun 2005 Location: Sacramento, CA Posts: 61	Yeah - I see extra holes and it is a 2wd frame. Is the top cross member in the attached picture the correct one? Attached Images

06-13-2005, 07:19 PM	#10
72longbed Account Suspended Join Date: Jun 2003 Location: PA Posts: 1,411	Top crossmember appears to be the correct 4x4 application. Nows the time to think about how close you want that distributor to the firewall. If you go with the stock 4x4 engine cradle location and you want to run an HEI, it will be very close to the firewall. I'll be moving mine so that the rear of the HEI is about 1.5" away from the firewall. Good luck with the fix, 72longbed

06-14-2005, 12:40 AM	#11
drink2mny Registered User Join Date: Jun 2003 Location: spokane wa Posts: 2,189	Could it be that his motor is that far up because...it is a 2 wheel drive frame and are setup a little different than a 4wd frame?? __________________ Support The Board

06-15-2005, 01:07 PM	#12
drink2mny Registered User Join Date: Jun 2003 Location: spokane wa Posts: 2,189	I would keep the motor and driveline where it is at, and put the crossmember in and put 2" of lift on her and call it good... Otherwise you will be heading into headache land, with moving everything back.. __________________ Support The Board

06-15-2005, 02:11 PM	#13
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	Ya wanna make sure you can still get your dizzy out if you move things back.

06-24-2005, 03:56 PM	#14
unixadm Registered User Join Date: Jun 2005 Location: Sacramento, CA Posts: 61	Guys - I removed the motor mount bolts and jacked the engine up. I have a bad motor mount on the passenger side that needs replacing. I grabbed the cross member that's in the photo above (top crossmember), however after measuring the inside of my frame rails (about 27 3/4", the cross member is up to 29" wide. So I'm wondering if this isn't a 73 or newer cross member. I have two cross members and 1 set of engine mount arms. It does look like going with the cross member would help some of my clearance issues - but I won't be sure until it's bolted in. I'm wondering if I can't shorten it up, drill some new holes and get it to fit. I guess the only thing I can waste is time. If anyone has a front 4x4 engine cross member for sale, please let me know. Last edited by unixadm; 06-24-2005 at 03:57 PM.

06-24-2005, 06:46 PM	#15
72longbed Account Suspended Join Date: Jun 2003 Location: PA Posts: 1,411	Moving Things Back?? I would never suggest moving things back?!?!? Where did that come from?? The only possible way that the driveline on a 67-72 4x4 could go is slightly forward. The crossmembers will both slide forward between the frame rails with no problem, and there are even a couple of bolt holes in the front frame rails from the factory that could be used. Going forward with the driveline, will bring the distributor AWAY FROM THE FIREWALL. Common sense, 72longbed



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06-24-2005, 07:48 PM	#16
unixadm Registered User Join Date: Jun 2005 Location: Sacramento, CA Posts: 61	72longbed - I'm going to leave the engine and drivetrain where it's at. The drivelines and everything else are working, so the only real reason for moving it that I saw was: 1. Clearance between the engine towers and the front diff pumpkin 2. Make the truck factory 4x4 correct After sliding in the second 4x4 cross member that I have backwards, it would appear that I'll have more clearance. The engine towers that are in the truck right now look half factory and half home made. Both of the towers have significant cracks in them. While I could weld them back up, there was obviously a flaw in the persons thinking who did the initial work. The 4x4 cross member that I have isn't the right one. However with some cutting and grinding, plus a little welding to fill in the old bolt holes I should be able to make it work. I'll get it to fit where I need it, lower the engine, install the cross member to motor mount bolts, make sure it's square and then drill 4 holes on each side and fasten with grade 8 hardware. I'm only learning how to weld and fabricate, but by holding up the home brewed mounts that were in there to this 4x4 cross member, the engine mount pads seem to line up which is a good thing. Hopefully I can knock this out tomorrow. I did get all of the hack job mounts out and bolted on two new motor mounts to the engine. All of the bolts were finger tight if that and one motor mount bolt was missing on the passenger side. Sweet. The motor must have been shifting around like crazy as not a single bolt was tight anywhere. I think there was a lot of beer in garage fridge during those weeks or months that this truck was being converted to 4wd.

06-25-2005, 03:03 PM	#17
unixadm Registered User Join Date: Jun 2005 Location: Sacramento, CA Posts: 61	Well I modified/shortened the cross member I had and was able to get it installed. Then I realized I put the damn thing in backwards so I had to take it out and swap it around. Duh. Considering this isn't the right cross member, it fit pretty well. I still need to drill the holes in the frame to mount it, but the engine is bolted to it with no issues. I did gain some clearance between the pumkin and the cross member, but not a whole lot. I'm hoping with the bump stops installed it won't hit. If it does, I'll just either take it very easy or put a 2-4" lift on the truck. At least the cross member is a lot more sturdy than those home made engine mount brackets that were on the truck! I'll get some pictures so you guys can see what I'm talking about.

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