[uforacing]

I have searched and seen one blurb that these will fit. Now I do understand that they are about 3" wider and that is fine because at least on the 86 2+2 the rear tires need to come out about 1.5" on each side anyway.

It looks to be a 1975 8.5 with a 3.42 LS. Anyone tried this yet?

[ligoatpar]

No I haven't tried this combo, but I think you're going to have the same issue that affects the '64-'72 rear install. Measure the distance between the upper contol arm mounts on the rear. I think you'l find they are wider than the stock 'G' body rear. This makes installing the upper control arms a project. Lotsa luck. Steve

[mike nixon]

Find a Grand National diff and shove it in there. That's a bolt in.

Mike

[monzaz]

Funny you should bring this up...I have your answers.

- trouble with the swap-
1. the upper control arm ears are too far forward and too wide apart
2. shock mounts are in front of the axle tubes instead of behind on the the g-body and 65-72 a-body
3. the 73-77 is 4" wider than your stock g-body diff easy.
4. not sure about the sping perches even being in the correct spot left to right either.
5. drive shaft mods will also need to be done since the 8.5 has a longer pinion then the 7.5 rear.

Problem solvers:
1. I have now had manufacturered sets of upper control arm (fully adjustable) this will take care of upper control arm situation. No Problem.
2. do already build complete housing using the 73-77 center section and narrow and mate the other brackets to the rear creating a bolt in rear for your G-body car.

Upper control arms are for sale for 150.00 a pair. they will solve that problem. If you are willing to do the rest then there you go.

If you want a housing it is 350.00 with axles it is 579.00 .

A whole rear built will be about 1000.00 with all new parts. not including the upper control arms.

This is still way cheaper than Moser Housings.

[monzaz]

Good luck finding the GN rear and in good condition after a GN got done stomping on it...lol. Prices are getting bad as 12 bolt chevy rears.

But YES if you find one at a good enough prive GRAB IT for a direct bolt in. You will still have the drive shaft issue to deal with too.

I have some VERY good posi parts for your 7.5 if you just want to do that. I have a 26 spine true trac for 350.00 New pretty much any gear ratio you want too. Liquidating that stuff. I do not sell enough . Take care and good luck on your hunt

Jim

[uforacing]

Originally Posted by monzaz

Good luck finding the GN rear and in good condition after a GN got done stomping on it...lol. Prices are getting bad as 12 bolt chevy rears.

But YES if you find one at a good enough prive GRAB IT for a direct bolt in. You will still have the drive shaft issue to deal with too.

I have some VERY good posi parts for your 7.5 if you just want to do that. I have a 26 spine true trac for 350.00 New pretty much any gear ratio you want too. Liquidating that stuff. I do not sell enough . Take care and good luck on your hunt

Jim

Thanks for the input. It has a stock 308 posi in it now and I am going to do a mild upgrade in HP/TQ but nothing major. The question was asked because I picked up the rear for $50 and as said it is a 3.42 LS. I have 1.5" spacers on the 7.5 now just to get the wheels (15X7 Pontiac) out where they should be.

Guess I need to find a 73-75 Grand Am to put this into. At least it doesn't eat...

[monzaz]

We make these... 8.5 12 bolt chevy and 8.8 ford centers that have all the exact same mounting points the g-body have in the lower control arms, spring perch and even the drum brakes. The only thing that needs modifying are the upper control arms as in most rears, the rest is done...
We sell Ice man conversion upper arms too. He has made our conversion uppers for our custom 8.5 center section rears.