Last Posi?

[scavani]

I'm down to two options for my 87 G-body rear end. I'm going to get one or the other. Just would like to hear any advice someone would like to share.

#1. 10 bolt rearend posi disk brake (323 gear)no brakes on it come off of 87 trans am good working condition,can fit in all f-body and g-body 82 92 camaro z28 iroc rs firebird formula gta monte carlo ss cutlas,

#2. I also have a 4:11 posi rear end. i will take $250 for the posi. no brake drums (this is out of a 78 Z-28.

If someone would like to talk about which one would be the most productive to swap into an 87 G-body I'd appreciate it and this is truly the last question on the subject 😀

 

[85 Cutlass Brougham]

Either one is a ton of work! I would skip BOTH of them. The one that is most worth it is the old F body rear from 1978 because it is a 8.5, but it is not set up for a 4 link rear suspension. It is set up for parallel leaf springs and would require extensive welding and modification to fit, plus cutting the housing AND axles down then resplining the axles. The 3rd gen F car axles is much the same story. It won't even come close to fitting as the car is about 8 inches wider than a G body, and the rear suspension does not use inner upper control arms like a G body; it uses a panhard rod and a torque arm instead. It would be cheaper to find a G body 8.5 rear end off E-Bay than to use either one of these.

 

[scavani]

Ok. Ebay seems to be the place but I'm not sure if I have a 8.5 or a 7.5?

 

[IrvJr]

I have an 8.5 for sale out my GN.

 

[Doober]

If it's stock Malibu it will have a 7.5. Most G-Bodies had 7.5s, the only ones that had 8.5s were T-Type Regals/GNs, and Cutlass 442s I believe. Unless you're building a sub-12 second car, you can rebuild a 7.5 with a new aftermarket posi, aftermarket axles, and a used set of gears for under $1,000. You'll spend close to that for a stock G-Body 8.5 usually. Any complete 8.5 under $800 is at least worth a look.

 

[85 Cutlass Brougham]

But why put the same money into the 7.5 as you would spend to buy a 8.5? If you max out the 7.5 you are left with nowhere to go but a new axle when you add power. If you start with a stock 8.5, you can improve it later for less than you would have to spend to upgrade from the 7.5. Either way, it's a lot of money.

 

[ididit]

buy c clip elim's!!!!!

even after mark. axles sould have eliminators installed hey if u spentt $$ on 26 spline moser u got it aprt put em in great protection i am no expert but 8.5 is a better investment if u can find one i have had to shorten the shaft due to the pinion lengh 7.5 hold up great unless u put stickies on the center section shreads hth

 

[Doober]

Yeah, there's something like 1" difference between a 7.5 and 8.5. If I ever make the power to, I'll upgrade the rear, but after building a 7.5 with new innards I won't be concerned about some used part failing as I would with an 8.5. If I bought an 8.5 at the very least I would put new bearings and seals in it, putting me well over what I would have into a 7.5, which I already have 2 of.