Floor pan mod needed? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

projectx · 10-08-2012, 08:42 PM

I'm still a newby to this model truck and have several questions. I've used the search button, so please bare with me.

I have a 68 swb fleet with a factory 6 cyl with 3 on the tree. I'm installing a 454 with a muncie 4 speed in the floor. Will I need to modify the floor pan? Will I have to install a "high hump" floor pan? If I need any modifications, where do I purchase?

projectx · 10-09-2012, 06:05 PM

No advice from anyone? I will have to test and trial I guess.

BossHogg69 · 10-09-2012, 07:16 PM

I don't have any experience with a BB & muncie trans, but I did install a 454 with a muncie '631' bellhousing on a TKO 500 and it BARELY cleared after a little persuasion with a shop hammer on the body seam/lip that runs on the inside of the trans tunnel on the low humps. I have since put a high hump in since I'm doing a frame off, but I had the combo in the low hump and drove it that way for 2 years with no problems. hope this helps.

projectx · 10-09-2012, 07:40 PM

Quote:

Originally Posted by BossHogg69

I don't have any experience with a BB & muncie trans, but I did install a 454 with a muncie '631' bellhousing on a TKO 500 and it BARELY cleared after a little persuasion with a shop hammer on the body seam/lip that runs on the inside of the trans tunnel on the low humps. I have since put a high hump in since I'm doing a frame off, but I had the combo in the low hump and drove it that way for 2 years with no problems. hope this helps.

Thanks. It does help. I'm doing a frame off also. I guess I'll look into installing a high hump as well. Appreciate the info.

54belair · 10-09-2012, 08:11 PM

Only mod for the trans will be the hole in the hump for the shifter. (low hump will work).

projectx · 10-09-2012, 08:24 PM

Quote:

Originally Posted by 54belair

Only mod for the trans will be the hole in the hump for the shifter. (low hump will work).

Good deal. Thanks for the info.

I may still install the high hump to allow for a shorter shifter. If I can find a high hump.

*Fitz* · 10-09-2012, 07:39 PM

Quote:

Originally Posted by projectx

I'm still a newby to this model truck and have several questions. I've used the search button, so please bare with me.

I have a 68 swb fleet with a factory 6 cyl with 3 on the tree. I'm installing a 454 with a muncie 4 speed in the floor. Will I need to modify the floor pan? Will I have to install a "high hump" floor pan? If I need any modifications, where do I purchase?

The 454 engine and bell housing will fit without any problems but I'm not sure about the muncie 4 speed. I used a BB and a turbo 400 on my 67 "low hump" which came from the factory with a straight six and three on the tree.
The trans should fit in a your floor but you will still need to mod for the shifter.

projectx · 10-11-2012, 11:32 PM

That is very true.....

67c10rustbuket · 10-11-2012, 11:45 PM

Are we talking an M20,21,22 Muncie 4 speed or those SM*#%? 4 speeds? The M20-22 are the same exterior size as a 3ott trans so there would be plenty of room. if you are going from a 6 to an 8 you will need the proper motor mount stands moved to the correct location (forward one hole)and then if so equipped the trans bellhousing xmember will need to move forward one hole as well. Either way on the trans and BB I have seen several install MT/BB without floor mods.

projectx · 10-11-2012, 11:58 PM

Not sure if it's a M20-21-22. The truck currently has a 327 with a 3 speed manual transmission. "Three on the tree". I think the mounts will work.?.? Have to investigate that.

67c10rustbuket · 10-12-2012, 12:17 AM

Motor mount stands are different for I6, SBC, BBC. You will need BBC mounts for the engine and installed in the proper frame hole. Here are some pics of trans, M20-22 Muncie., 3OTT Saginaw, and Muncie SM465. Which does your 4 spd look like? The last pic probably (SM465 Muncie) needs a high hump tunnel. I have a high hump for my truck but I needed it because I have a 4L60E that was way to close to the floor (couldnt get the trans mount in without rubbing the cab floor).

projectx · 10-12-2012, 12:20 AM

Had no idea there was a difference between sbc and bbc mount stands. That's good to know.

My transmission looks like the first picure. Except not as clean.

67c10rustbuket · 10-12-2012, 12:47 AM

That trans will fit fine under the stock low floor, no mods needed other than a hole for the shifter. I was going to run one of those but changed plans. I could not find any shifters for a truck but was looking at a shifter for a 55-57 chevy (car) bench seat that had the longer handle. either way buy a shifter and they (B&M or others etc) offer different length shifter handles.

Here is a link about the different motor mount stands, take a look. You can find the BBC stands in the classifieds on here all the time.

http://67-72chevytrucks.com/vboard/s...d.php?t=437680

If you were to remove your 6cyl engine stands you will notice there are 3 evenly spaced holes on the top of the frame. A 6cyl goes in the rear 2 holes and an SBC or BBC goes in the front 2 holes. if you look at yours with the 6 installed there is a hole in front of your mount stands. this wiil be the new front mount hole for a V8. You can use the current mounting and drill the crossmember for BBC stands but you will have a heck of a time working on you dist but then again it does help with weight distribution with the engine in the rear location.

67c10rustbuket · 10-12-2012, 12:50 AM

If your 3OTT has a bell housing mount Xmember (cast iron) you will need to also move it forward one hole. You could also use a Camaro aluminum bell and remove the bell Xmember and use a tail trans mount Xmember which would be a better choice anyway with the BBC torque.

projectx · 10-12-2012, 10:34 AM

Quote:

Originally Posted by 67c10rustbuket

If your 3OTT has a bell housing mount Xmember (cast iron) you will need to also move it forward one hole. You could also use a Camaro aluminum bell and remove the bell Xmember and use a tail trans mount Xmember which would be a better choice anyway with the BBC torque.

The first transmission pictured is a Muncie, correct? I really didn't want to run the 30tt Saginaw.

67c10rustbuket · 10-12-2012, 11:34 PM

Quote:

Originally Posted by projectx

The first transmission pictured is a Muncie, correct? I really didn't want to run the 30tt Saginaw.

Yep, thats a Muncie M20. They are physically the same as the 3ott trans but they have a third shift lever right of the midplate for the reverse gear. Also these versions have an aluminum case where the 3ott Sag has an iron case. The numbers you should look for are on the opposite side of the main housing like so(casting): GM CORP PATENT PEDING 3851325" or something like that, I sold mine some time ago. waaah. and also next to the midplate (plate between the main case and tail housing) there is a stamping with date code and ratio codes. Check this link for more info on those.

http://www.5speeds.com/muncie.htm

There are a few differences such as the input shaft spline count, shaft diameter, tail housing length for BOP cars, support shaft bearing size (some fit in iron 3ott bell housings some dont) Ratios etc etc.

67c10rustbuket · 10-12-2012, 12:52 AM

Get the numbers off of your Muncie trans and let us know what they are and we can help ID it for you. I will check back tomorrow. Good night!

projectx · 10-12-2012, 10:31 AM

Thanks rustbuket. Tons of helpful information coming from you. I really appreciate you taking the time to clue me in. I'll get the transmission numbers and report back.

67c10rustbuket · 10-12-2012, 11:36 PM

Quote:

Originally Posted by projectx

Thanks rustbuket. Tons of helpful information coming from you. I really appreciate you taking the time to clue me in. I'll get the transmission numbers and report back.

No problem, this is what the forum is for! sharing good info and bad mistakes. I have some of both

cdowns · 10-13-2012, 08:30 AM

as far as shift lever height// any number of levers different heights and contours are commonly available for these shift linkages or it is one of the easiest things ever to fab up as the lever is attached to the linkage with two bolts

10-08-2012, 08:42 PM	#1
projectx Registered User Join Date: Jun 2012 Location: Washington, NC Posts: 35	Floor pan mod needed? I'm still a newby to this model truck and have several questions. I've used the search button, so please bare with me. I have a 68 swb fleet with a factory 6 cyl with 3 on the tree. I'm installing a 454 with a muncie 4 speed in the floor. Will I need to modify the floor pan? Will I have to install a "high hump" floor pan? If I need any modifications, where do I purchase?

10-09-2012, 06:05 PM	#2
projectx Registered User Join Date: Jun 2012 Location: Washington, NC Posts: 35	Re: Floor pan mod needed? No advice from anyone? I will have to test and trial I guess.

10-09-2012, 07:16 PM	#3
BossHogg69 motor exploder Join Date: Mar 2009 Location: Pittsburgh, PA Posts: 2,346	Re: Floor pan mod needed? I don't have any experience with a BB & muncie trans, but I did install a 454 with a muncie '631' bellhousing on a TKO 500 and it BARELY cleared after a little persuasion with a shop hammer on the body seam/lip that runs on the inside of the trans tunnel on the low humps. I have since put a high hump in since I'm doing a frame off, but I had the combo in the low hump and drove it that way for 2 years with no problems. hope this helps. __________________ Adam 1969 Chevy CST/10 stepside, DART Big M/TREMEC Magnum Extreme/3.73's w/Detroit Truetrac 1965 Chevy Bel Air Wagon (daily driver), 327/TH350,10 bolt w/3.08's 1961 Chevy Bel Air Sport Coupe, ZZ454/M21/9" rear w/3.50's & Detroit Truetrac 2005 GMC 1500 ccsb 2wd, 6.0L/4L65e/3.73 G80 2006 GMC 2500HD ccsb 4x4, DMax LBZ/Allison 6spd/4.56's w/Detroit TrueTrac Use the SEARCH function on this forum - it is your friend!!

10-09-2012, 08:11 PM	#5
54belair Registered User Join Date: Mar 2011 Location: bolivar, mo Posts: 839	Re: Floor pan mod needed? Only mod for the trans will be the hole in the hump for the shifter. (low hump will work). __________________ 1997 shortie stepside 1968 short stepside 1966 mustang 1966 chevelle ss Dont always go the cheapest route--You can save yourself into the poorhouse! My Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=489030

10-11-2012, 11:32 PM	#8
projectx Registered User Join Date: Jun 2012 Location: Washington, NC Posts: 35	Re: Floor pan mod needed? That is very true.....

10-11-2012, 11:45 PM	#9
67c10rustbuket Registered User Join Date: Apr 2011 Location: Mustang, Oklahoma Posts: 2,806	Re: Floor pan mod needed? Are we talking an M20,21,22 Muncie 4 speed or those SM*#%? 4 speeds? The M20-22 are the same exterior size as a 3ott trans so there would be plenty of room. if you are going from a 6 to an 8 you will need the proper motor mount stands moved to the correct location (forward one hole)and then if so equipped the trans bellhousing xmember will need to move forward one hole as well. Either way on the trans and BB I have seen several install MT/BB without floor mods. __________________ Dan <---(my name) 67 SWB C10 project "GEORGIA"-59 Brookwood 2dr wag...Next project-03 Tahoe 4x4 5.3 family ride-07 Hondur Accord, commuter car

10-11-2012, 11:58 PM	#10
projectx Registered User Join Date: Jun 2012 Location: Washington, NC Posts: 35	Re: Floor pan mod needed? Not sure if it's a M20-21-22. The truck currently has a 327 with a 3 speed manual transmission. "Three on the tree". I think the mounts will work.?.? Have to investigate that.

10-12-2012, 12:17 AM	#11
67c10rustbuket Registered User Join Date: Apr 2011 Location: Mustang, Oklahoma Posts: 2,806	Re: Floor pan mod needed? Motor mount stands are different for I6, SBC, BBC. You will need BBC mounts for the engine and installed in the proper frame hole. Here are some pics of trans, M20-22 Muncie., 3OTT Saginaw, and Muncie SM465. Which does your 4 spd look like? The last pic probably (SM465 Muncie) needs a high hump tunnel. I have a high hump for my truck but I needed it because I have a 4L60E that was way to close to the floor (couldnt get the trans mount in without rubbing the cab floor). Attached Images __________________ Dan <---(my name) 67 SWB C10 project "GEORGIA"-59 Brookwood 2dr wag...Next project-03 Tahoe 4x4 5.3 family ride-07 Hondur Accord, commuter car Last edited by 67c10rustbuket; 10-12-2012 at 12:19 AM. Reason: spelling

10-12-2012, 12:20 AM	#12
projectx Registered User Join Date: Jun 2012 Location: Washington, NC Posts: 35	Re: Floor pan mod needed? Had no idea there was a difference between sbc and bbc mount stands. That's good to know. My transmission looks like the first picure. Except not as clean.

10-12-2012, 12:47 AM	#13
67c10rustbuket Registered User Join Date: Apr 2011 Location: Mustang, Oklahoma Posts: 2,806	Re: Floor pan mod needed? That trans will fit fine under the stock low floor, no mods needed other than a hole for the shifter. I was going to run one of those but changed plans. I could not find any shifters for a truck but was looking at a shifter for a 55-57 chevy (car) bench seat that had the longer handle. either way buy a shifter and they (B&M or others etc) offer different length shifter handles. Here is a link about the different motor mount stands, take a look. You can find the BBC stands in the classifieds on here all the time. http://67-72chevytrucks.com/vboard/s...d.php?t=437680 If you were to remove your 6cyl engine stands you will notice there are 3 evenly spaced holes on the top of the frame. A 6cyl goes in the rear 2 holes and an SBC or BBC goes in the front 2 holes. if you look at yours with the 6 installed there is a hole in front of your mount stands. this wiil be the new front mount hole for a V8. You can use the current mounting and drill the crossmember for BBC stands but you will have a heck of a time working on you dist but then again it does help with weight distribution with the engine in the rear location. __________________ Dan <---(my name) 67 SWB C10 project "GEORGIA"-59 Brookwood 2dr wag...Next project-03 Tahoe 4x4 5.3 family ride-07 Hondur Accord, commuter car

10-12-2012, 12:50 AM	#14
67c10rustbuket Registered User Join Date: Apr 2011 Location: Mustang, Oklahoma Posts: 2,806	Re: Floor pan mod needed? If your 3OTT has a bell housing mount Xmember (cast iron) you will need to also move it forward one hole. You could also use a Camaro aluminum bell and remove the bell Xmember and use a tail trans mount Xmember which would be a better choice anyway with the BBC torque. __________________ Dan <---(my name) 67 SWB C10 project "GEORGIA"-59 Brookwood 2dr wag...Next project-03 Tahoe 4x4 5.3 family ride-07 Hondur Accord, commuter car

10-12-2012, 12:52 AM	#17
67c10rustbuket Registered User Join Date: Apr 2011 Location: Mustang, Oklahoma Posts: 2,806	Re: Floor pan mod needed? Get the numbers off of your Muncie trans and let us know what they are and we can help ID it for you. I will check back tomorrow. Good night! __________________ Dan <---(my name) 67 SWB C10 project "GEORGIA"-59 Brookwood 2dr wag...Next project-03 Tahoe 4x4 5.3 family ride-07 Hondur Accord, commuter car

10-12-2012, 10:31 AM	#18
projectx Registered User Join Date: Jun 2012 Location: Washington, NC Posts: 35	Re: Floor pan mod needed? Thanks rustbuket. Tons of helpful information coming from you. I really appreciate you taking the time to clue me in. I'll get the transmission numbers and report back.

10-13-2012, 08:30 AM	#20
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Floor pan mod needed? as far as shift lever height// any number of levers different heights and contours are commonly available for these shift linkages or it is one of the easiest things ever to fab up as the lever is attached to the linkage with two bolts __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY



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