What donor axle for my 64?

[62gmc910]

Originally Posted by GMCMG

Thanks; I hadn't given that enough thought. My brother-in-law has a 94 Sonoma, and I looked at the axle (probably too light), and it wasn't wide enough. I never gave a thought to the springs. I've got his bed off in my garage right now (fuel sending unit problems), so when I get home tonight I'll take some measurements.

I don't mean to tell you how to build your truck but the trailing arm suspension is about as good as it gets, the S truck rear axle will handle the 6.2s torque the 4.3 trucks had the same 10 bolt diff as the 1/2 tons that came with the 6.2 and I think your gearing would be a little too tall ' the 6.2 is pretty soggy in the lower rpm ranges unless its turboed. I have seen the 78ish 1/2 ton rears used with 7" ralley wheels widened on the inside that way you keep the same bolt pattern. Some of the caprice/impalas had the truck bolt pattern and I think they are narrower than the trucks

[hill64step]

Originally Posted by 62gmc910

Some of the caprice/impalas had the truck bolt pattern and I think they are narrower than the trucks

What years, and any more details about these? I don't know much when it comes to dealing with rear ends/axles, but I know I want to change for 5 lug and better mpg. I had planned to go with the early 70s 5 lug rear, but I heard it was wider.

[62gmc910]

Originally Posted by hill64step

What years, and any more details about these? I don't know much when it comes to dealing with rear ends/axles, but I know I want to change for 5 lug and better mpg. I had planned to go with the early 70s 5 lug rear, but I heard it was wider.

Don't know for sure on the year of the Impala rear ends I think they came in cop cars and wagons, but unless you need narrower track the 71 -72 5 bolt coil bolts right in, And as firefighter said the 73-87 12 and 10 bolts track the same as the discs, If you use the truck rear look for one with wider drums

[GMCMG]

Originally Posted by 62gmc910

I don't mean to tell you how to build your truck

That's actually exactly what I'm looking for on here. As much input as possible. I've not ever done a build anything like this before, and there are a lot of things I don't know/haven't figured out. Every suggestion/criticism/comment I can get is appreciated.
You're not the first to tell me the 6.2 will be sluggish at the lower rpms, and I've finally heard enough to talk a little sense into me, so I'm going to go to a 2.73, which I think will keep my rpms around 16-1700 at 65. Does that sound like a more rational range?

Originally Posted by Tx Firefighter

Yes, the 73-87 rearend is wider...for that 78 front suspension you're going to run...a 2.73 ratio. If you can live with that, the truck 12 bolt is perfect for your application...

Yeah, I'm definitely talked into sticking with the 78 and trying to find some 2.73 gears to put in it.

Thanks to EVERYONE who has provided answers!