Rear Suspension Controversy

[AusTruck]

My 69 C-10 has the factory truck arm suspension; peg-leg, i.e. non-posi.

Like most owners here, I'd love to have a posi rear. And 5 lugs do open a lot of wheel options. So a friend has a 78 3/4 ton truck with a factory posi rear end in it. I've rode and driven the truck and I know the guy takes pretty good care of his stuff. At least until he hit..........a cow. Yeah, he hit a cow. You can guess what about 1500 lbs of beef on the hoof does to a front end. Thank heavens no one was hurt but the cow was DOA.

Well he's offered me the rear end for free, as the front is pretty much toast. But its a leaf spring rear. I've heard that I can swap out the spring perches to my 69 and the rear will go in, albeit with the extra width of the 73 and up rears. I get 5 lugs and a posi in the deal. Probably need a new driveshaft too for the different U-joints. I'd really rather just do a nuts-and-bolts swap rather than weld on new truck arm mounts to the 3/4 ton rear. Yeah, I'd probably have to do some shock mount fabrication.

It seems like a lot of folks here wouldn't swap the truck arm suspension for anything. I can guess the truck arms are pretty good at the strip. I never raced the truck but have always wanted to make a pass just to see what it'd do.

So what do folks think here? Go to the leaf springs for a free heavy-duty posi rear (yes, it is certain to be posi) or just stay with what I've got (non-posi basic 6-lug rear)? Chevy built zillions of trucks with leaf springs after 72, so they must have been ok. Do the leafs change the ride and characteristics that much? Leafs do seem to open up exhaust options too.

[N2TRUX]

I'm a bit confused here. If the donor truck is a "78 3/4 ton" its not a 5 lug. If its a 1/2 ton it will be 5x5. Regardless, there is a lot of work involved either way. To convert your to leaf your going to need the correct 67-71 hangers. To convert the 78 axle to T/A you will need the correct perches and a modified or aftermarket trackbar.

If it were me, I would try to locate the correct housing or build yours with new 5 lug axles

[AusTruck]

2WD not 4WD.

[SCOTI]

Originally Posted by AusTruck

2WD not 4WD.

You'd have to convert the leaf axle to the T/A set-up, or swap the chassis from T/A's to leafs. Swapping T/A mounts to the rear housing would be the easier task of the two choices. Some guys swear by their leafs, others prefer T/A's.

I had one of each @ the same time (68 short fleet, 74 short fleet). They were built using the same equipment choices w/the same type of drops. Other than the rear suspensions, they were VERY similar. The T/A truck rode better w/o a doubt.

Regardless.... the 'free' axle your proposing to swap is from a 3/4 which utilizes 8-lug wheels. That will cost you money to convert or overcome.

[N2TRUX]

Originally Posted by AusTruck

2WD not 4WD.

If its a C20 (2wd) it will have 8 lugs. While you might be able to convert this to 5 lug, you still might have issues with the larger drum fitting your wheels if they are 15".

We are not trying to be discouraging, but often times "free" is not so much a bargain as it appears.

[dennislbrooks]

The posi is probably a gov lock --- not somethiong I want. You can buy aftermarket 5 lug axles or have your centers turned to accept 72 drums, weld one lug hole and place the 5x5 bolt pattern on the old 6. Only the one lug overlaps --- now the welded one. Do not waste time welding all holes shut.

I guess you have 3.73 gears now.

I am looking for a posi also and have narrowed my choices to an eaton coil, dana true trac or an auburn cone. Others will have diff opinions.

If your truck is going to remain a 2wd, I would stay with the better ride --- coils. A c10 frame is bowed out at the rear not parallel like a k10 frame. You will need to modify the leaf mount you use. 67-87.

I can add a pic if wanted.