what 8.5" WILL fit?

[JBreu]

http://www.umiperformance.com/catalog/index.php?main_page=product_info&cPath=8_60_68&products_id=76

So is this all I would need? The spring perches aren't anything to worry about? Like I said I noticed they were positioned a little ahead of the axle tunnels compared to the gbody ones which are right on top. If that's all it takes I believe I will install a 12 bolt, was also looking and seems its possible to slap blazer discs on those rear ends

Yes that's all you would need...I would buy the kit that includes the lower arms as well, not needed though,,Just to help prevent wheel hop that is copmmonly associated with the wimpy stock control arms...Spring perches are fine where they are. You aill also need a different rear U-Joint for the 12 bolt rear...Napa sells them, their brand part # 372. Hope this helps 8)

 

[grand86prix_05]

Awesome, thanks for the great info. Looks like that's what I'm going to be doing, seems like the best route and are much easier to find. I'll have to consider the lowers, not building a drag car or anything just gonna put in a solid engine and prefer not to pop a bunch of 7.5s lol thanks again

 

[grand86prix_05]

Now I have one more question, I found a great deal on an 8.5 out of a 72 chevelle. I know it'll be wider but if only by 2 inches that's perfectly fine by me, but will I need different control arms for it too? And if so any idea if the 12 bolt ones work? Thanks

 

[Grandprixpaul]

So chevelle 66-72 rear ends wl bolt right in do i need to modifiy anything and do you guys know how much wider they are ?

 

[grand86prix_05]

From what I understand paul you just need different control arms and that's it, also heard 66 rear ends are no wider than gbody rears but the others are 2 inches wider overall than a gbody rear

 

[khan0165]

78-88 Gbody 10bolt ---> 58 inch wide
64-67 Abody 12bolt ---> 60.5 inch wide
68-72 Abody 12bolt ---> 62.5 inch wide

with 8.5 10bolt, you need to shorten driveshaft 1 inch over what you had with 7.5 10bolt
... I don't know what it is for a 12bolt

 

[pontiacgp]

64-67 Abody 12bolt ---> 60.5 inch wide
68-72 Abody 12bolt ---> 62.5 inch wide

those also came with a 10 bolt 8.2 rear end which is cheaper and lighter than the 12 bolt so depending on the power you're running it may be an option

 

[JBreu]

The driveshaft will NOT have to be cut if you install a 12 bolt.... 8)

 

[grand86prix_05]

Crap...I don't want to have to shorten my drive shaft. Well I assumed it to be an 8.5 anyway, he said 10 bolt out of a 72 chevelle. Sounds like I may have to back out of the deal, sucks though because he only wants 100 out of it. Then again I could probably sell it for a good chunk more

 

[khan0165]

if I swap a 7.5 with a 12bolt, driveshaft doesn't need shortening?
what if I swap a 8.5 with a 12bolt?

I was told that swaping 7.5 with 8.5 requires 1" shorter driveshaft

... $100 is very good deal for a 8.5 10bolt... I would still buy it. It's not expensive to have the driveshaft altered and rebalanced.