'70 rear end woes

[BowTieOgre]

Im at the point in my build where I need to replace or reinstall the rear end and I am having trouble deciding what to do.

Originally I was just going to slide in the 10 bolt I have from a '96 Caprice with discs (I already have the saddles and panhard bar) but now that I found out it isnt a limited slip like I thought.

I still have the 12 bolt 6 lug open end 3.73 coil spring rear from the original truck but I really want to go with 5 lugs. I found a 12 bolt 5 lug 3.08 non posi rear on a '79 at the junkyard but no discs....what do you guys think I should do on a limited budget?

[70rs/ss]

Sell me the rear discs of the Caprice!! Just kidding, the 6-lug rear can have the axles replaced with new after market 5-lugs, and a posi or just find a posi rear and put it in. The disc part will work if you look up Glock35 (can't remember his whole used name; look in the parts board, he has an add!!) who sells brackets to hook up the discs from the caprice to a 12 bolt. PM me or call me and we can go deeper into this as it is way easier for me to talk than type!!

[skchevota]

why not just buy a possi for the caprice 10 bolt? or build the stocker with a possi, most rearend shops can re drill your 6 lug axles to 5 lug, and then addapt the disks. or get the junk yard 12 bolt, adapt you disks to it and add a possi, look on ebay,craigs list,ect to find parts to build these cheap.

[Longhorn Man]

POSI is nice to have, but shouldn't be a deal breaker.
I would skip the rear disks unless you do alot of off roading, haul 5000 pounds of stuff all the time, or REALLY like the bling look. Disks do little to nothing on a street truck that is unloaded.
Personally, I'd locate a 5 lug 3.07 rear that came out of one of these trucks. Shouldn't be too hard to find down there.
Or, maybe grab your original axle, determine if it is a narrow or wide rear... if it is a wide one, just slip 5 lug axles in it (no need for aftermarket stuff) and either swap out the carrier and gear, or just run the 3.73, which is ideal if your rebuild includes an overdrive.

[BowTieOgre]

Originally Posted by Longhorn Man

POSI is nice to have, but shouldn't be a deal breaker.
I would skip the rear disks unless you do alot of off roading, haul 5000 pounds of stuff all the time, or REALLY like the blink look. Disks do little to nothing on a street truck that is unloaded.
Personally, I'd locate a 5 lug 3.07 rear that came out of one of these trucks. Shouldn't be too hard to find down there.
Or, maybe grab your original axle, determine if it is a narrow or wide rear... if it is a wide one, just slip 5 lug axles in it (no need for aftermarket stuff) and either swap out the carrier and gear, or just run the 3.73, which is ideal if your rebuild includes an overdrive.

Yeah I would like the option of towing and love the idea of 4 wheel discs so I think I might stick to that. I remember that the rear end width changed in '70 but i cant remember where to find the widths...any ideas? I could live without posi but HAVE to have 5 lug. Im guessing since I have the axle saddles already I could snag a 12 bolt out of any GM truck/suv and do some grinding and welding. Thanks for the input guys.

[BowTieOgre]

Well it looks like I will either buy a posi 12 bolt for $800 or build one for about the same. Im thinking I would rather build one so i would be more familiar with it when/if something went south but that means wait time and reconditioning the housing. Any opinions?

[mnunn454]

I hear 4 different pieces of this question:
Do I want posi or not?
Do I need the strength of a 12-bolt, or will the 10-bolt be strong enough?
Do I have to have 5 lug axles or am I willing to live with 6?
Do I want rear disk brakes bad enough to swap in the whole Caprice axle?

I'd start by ranking these factors in order of which is most important, and then try to tie a cost to each. Rear disk brake kit for about $400-$500, Eaton Posi for about $400 (10-bolt or 12) plus $300 to $500 for setup (unless you do that yourself), Set of new 12-bolt axles for about $300 to $350 (once you pay for new studs and shipping).

Were it me, I'd stay with the original 12-bolt housing and add 5-lug axles. I'd then add a posi and rear disk brakes later, as needs dictate and resources allow.

If you can find a good 10" posi with disk brakes and the gearing you want for less than $500, then I'd go that way as long as you can install it and it'll handle your torque requirements.

JMO.