First Post - a lot of 4x4 and 3/4 ton questions

[Ol Blue K20]

I don't know how I missed this but, welcome and nice truck!

[Old_iron]

Originally Posted by Chknlyps2

With a 31.5" tall tire and the 1 to 1 4th gear ratio that your SM465 has, at 55 mph your rpm with different gear ratios will be as follows.

3.73 = 2188 rpm

4.10 = 2405 rpm

4.56 = 2675 rpm

I also think 4.10's would be your best bet.

Thank you, thats great information to have. The rpm for 4.10s seems a little high to me but I guess that is the trade off for more power transfer at slower speeds? 3.73s would probably limit my low end power?

Dale, thanks for the welcome!

[Old_iron]

Along with my question above, are open knuckle D44s in the front weaker than my closed knuckle 44 will be for how I'm going to be using it?

[Ol Blue K20]

I don't think either is weaker than the other. I prefer the disc brakes on 71-72. But I see no difference between the open and closed drums other than turning radius.

[Old_iron]

I searched the site a bunch and looked in the FAQs and cant find an answer to this question:
Will a 350 v8 pulled from a 1981 chevy pickup (with the engine towers) fit right into my truck (bell housing aside)?
And, will my V6 radiator work vit the 350 or should I get the one out of the 81?

[Chknlyps2]

Originally Posted by Old_iron

I searched the site a bunch and looked in the FAQs and cant find an answer to this question:
Will a 350 v8 pulled from a 1981 chevy pickup (with the engine towers) fit right into my truck (bell housing aside)?
And, will my V6 radiator work vit the 350 or should I get the one out of the 81?

First 2 pics are of a 70 with a 350 that a previous owner put a 73 to 87 radiator and shroud in. It fits but is to tall to use the stock upper mounts, might be able to use some spacers under the upper mounts if you absolutely had to. I have a stock one for this truck to install once I get a few of the bugs worked out.

The last 3 pics are of my 72 K20, if your inlet, outlet and shroud look like this they should work. I have had 2 GMC V6's in the past but they were both 66's, I have not looked under the hood of this model GMC with a V6 yet.

Not sure on the motor mount towers, I remember reading about a guy using spacers for square body towers because they were taller but that might have been in a 60 to 66 truck, and may have been 2wd also. I have a couple square body K20's and the 72 K20 here so tomorrow if I get home at a decent hour I can measure if an answer does not pop up.

[Old_iron]

Thank you sir, those pictures will be very helpful. Going on Wednesday to pull/buy the 350 and also to stop by to visit my 68 to figure out exactly what i have underneath it. I am sure i will have more questions after that.

Appreciate all the help everyone has been. This is a great forum.

[collin70k/20]

Nice truck I like it!

[drfloyd]

Originally Posted by Old_iron

Thank you sir, those pictures will be very helpful. Going on Wednesday to pull/buy the 350

Wish I were closer to you. I have several 350 and BB engines that I will never be using.

[Old_iron]

Originally Posted by collin70k/20

Nice truck I like it!

Thanks. I looked at your build thread, good job on your truck so far. I was your age when I started the complete rebuild of my Chevelle. It took about 5 years to finish it and I learned a lot about patience and hard work from doing it. I have a friend who started out doing stuff like what you are doing at a young age and he went on to a vocational school and now builds race cars for a living and works in the race industry traveling to races around the country. Anything is possible if you work hard and don't give up.

Originally Posted by drfloyd

Wish I were closer to you. I have several 350 and BB engines that I will never be using.

Me too! It's local and the price is not too bad.

[Old_iron]

I spent some time crawling around under the truck yesterday and found out what I have.

It has 4.56 gears (D44 front, D60 rear) with an open rear. I (think) that's original. Closed knuckle up front. I might be swapping axles in the future to get 4.10s with Posi in the rear and open knuckle/disc in the front. Are there years/models that will bolt-in, anything to look out for?

I took some pictures of the rear spring set up, it looks like it has overload springs that were added but does not have the bumper parts bolted to the frame? The main leafs are around 3" wide, the overloads are 2 1/2" - 2 3/4". What are they?

I think I'm going to end up going with a 4" suspension lift. The goals are extra-clearance, and strength. The truck needs to be able to carry a lot more than it's own weight. The Tough Country HD springs look like they might fit the bill?

With my goals should I keep the rear spring set up and add the 3-4" lift blocks that come in the kit, or is there a more robust/stronger solution that accomplishes the strength and lift goals?

It looks like my frame does not have a bump-in for a power steering gearbox. What do I need to do to run power steering, and what truck would be the right donor for the parts?

[Chknlyps2]

Originally Posted by Old_iron

I spent some time crawling around under the truck yesterday and found out what I have.

It has 4.56 gears (D44 front, D60 rear) with an open rear. I (think) that's original. Closed knuckle up front. I might be swapping axles in the future to get 4.10s with Posi in the rear and open knuckle/disc in the front. Are there years/models that will bolt-in, anything to look out for?

I took some pictures of the rear spring set up, it looks like it has overload springs that were added but does not have the bumper parts bolted to the frame? The main leafs are around 3" wide, the overloads are 2 1/2" - 2 3/4". What are they?

I think I'm going to end up going with a 4" suspension lift. The goals are extra-clearance, and strength. The truck needs to be able to carry a lot more than it's own weight. The Tough Country HD springs look like they might fit the bill?

With my goals should I keep the rear spring set up and add the 3-4" lift blocks that come in the kit, or is there a more robust/stronger solution that accomplishes the strength and lift goals?I am not a fan of blocks higher than 2 inches, you could do a rear shackle flip from DIY4x4 or ORD, The ORD link has an explanation of how you get 4 inches of lift with your springs by flipping the shackles, you may also have to add a wedge or shim to correct pinyon angle. http://diy4x.com/product.php?product...cat=250&page=3

http://www.offroaddesign.com/catalog/shacklekit.htm

It looks like my frame does not have a bump-in for a power steering gearbox. What do I need to do to run power steering, and what truck would be the right donor for the parts? The bump or pocket in the frame is for the wider section on the power steering box. Member here by the name of Captainfab makes a bracket to space the box away from the frame. He has them listed in the 60-66 parts section but I think they are good for the 67-68 flat frame trucks. Contact him and pick his brain. http://67-72chevytrucks.com/vboard/s...d.php?t=332923

Some answers above.

I have some pics showing the difference between 67-72 and 73-87 K20 motor mounts and crossmembers, I will post them in a little bit.

[k29349]

If you are going to pull heavy trailers and plow snow, I would keep the 4.56 gears and put Detroit True-Tracs in them. The lower gear ratio makes it easier on every other drive train component ahead of it. Do yourself a favor and use Spicer U-joints, or you will be changing them every year also.

[Chknlyps2]

Originally Posted by Old_iron

I searched the site a bunch and looked in the FAQs and cant find an answer to this question:
Will a 350 v8 pulled from a 1981 chevy pickup (with the engine towers) fit right into my truck (bell housing aside)?
And, will my V6 radiator work vit the 350 or should I get the one out of the 81?

The first 2 pics are of a 72 K20 cross member and mounts, the last 2 are of a 75. The 72 cross member is straight from left to right, the 75 angles forward and goes under the motor at the front of the oil pan. The bolt holes from frame to frame are close on width but it is hard to be accurate bending the tape around the lines in the way. I think with possibly drilling a new hole or 2 and a spacer because the 75 frame looks close to a half inch taller it should work.

[Old_iron]

Thank you for the pictures. Is there any difference between a 72 3/4ton and 72 1/2 ton v8 engine tower?

[Old_iron]

I'm going to go with 4.10 axles, the Dana 44 open knuckle disc (3/4 ton) for the front. However, for the rear it seems like I have some options available in my area.

D60 Full Float Open
D60 FF Factory Posi from a '68 3/4 ton
Corporate FF 14-Bolt Open
Corporate FF 14-Bolt Gov-loc

For very heavy duty hauling, towing and snow plowing, what would you go with?

[k29349]

Gov 14 bolt.

[haysonj]

Originally Posted by Old_iron

I'm going to go with 4.10 axles, the Dana 44 open knuckle disc (3/4 ton) for the front. However, for the rear it seems like I have some options available in my area.

D60 Full Float Open
D60 FF Factory Posi from a '68 3/4 ton
Corporate FF 14-Bolt Open
Corporate FF 14-Bolt Gov-loc

For very heavy duty hauling, towing and snow plowing, what would you go with?

You will have a better choice of gears with the 14 bolt You will also have to move the perches on the axle. Here is a picture of mine from a 73 one ton.

[Chknlyps2]

Originally Posted by Old_iron

I'm going to go with 4.10 axles, the Dana 44 open knuckle disc (3/4 ton) for the front. However, for the rear it seems like I have some options available in my area.

D60 Full Float Open
D60 FF Factory Posi from a '68 3/4 ton
Corporate FF 14-Bolt Open
Corporate FF 14-Bolt Gov-loc

For very heavy duty hauling, towing and snow plowing, what would you go with?

I like 14 bolts but I don't like gov locks, I grenaded one once do to one tire having traction and the other not right when i decided to nail the throttle to climb a hill. I vote for the Dana 60 posi. One because it is a direct bolt in without modifying spring perches or driveline and two because it is keeping closer to the way the truck was originally built.

Originally Posted by haysonj

You will have a better choice of gears with the 14 bolt You will also have to move the perches on the axle. Here is a picture of mine from a 73 one ton.

Did you go from a Dana 60, just wondering if you had to shorten the driveline?

[haysonj]

Originally Posted by Chknlyps2

I like 14 bolts but I don't like gov locks, I grenaded one once do to one tire having traction and the other not right when i decided to nail the throttle to climb a hill. I vote for the Dana 60 posi. One because it is a direct bolt in without modifying spring perches or driveline and two because it is keeping closer to the way the truck was originally built.



Did you go from a Dana 60, just wondering if you had to shorten the driveline?

I had custom drive shafts built with CV joints due to the GV overdrive and a 4 in lift. My original was a HO52

[69K20Builder]

A 4 inch lift for that truck shouldn't break the 500 dollar mark. It will consist of front springs, 4 shocks, blocks for the rest and a pitman arm extension. I just bought a 69 k20 short wheel base stepside two weeks ago for 500 dollars. Has dana 44 hd front with disc brakes and a 12 bolt rear. Mine was rougher looking at home than it looked in the woods surrounded by other rust piles but nothing a welder and patch panels can't fix. I may have it done by the first of the year if all goes as planned.

[Old_iron]

Nice deal you got there!

Does anyone know why my rear leafs look the way they do? Previous owner upgrade? Do they need the bumpers?

[Stocker]

Yep, likely a PO upgrade, but he didn't finish the job -- those overloads do need the bumpers in order to work as designed. Just a guess but they are probably gonna be hard to find. Best bet might be to get some off a different type of truck, any brand, one-ton or larger. With any luck, you can find some that will fit.