Rear Axle Identification

Injectedcutty

G body LS mafia
Supporting Member
Nov 24, 2014
5,947
113
Louisville, KY
I'm going to look at a non-running 1986 442 tomorrow; If I were to pick it up, and bolt in the 8.5, would the driveshaft proper fit from a 200r4-8.5 to a TH200-7.5?

Thanks!
Don't believe so, the 8.5 has a longer pinion on it requiring the driveshaft to be shortened about an inch. At least i had to shorten mine an inch when i swapped out my 7.5 in my 87 cutlass to a 8.5 i got from an '85 442 with 3.73's in it. Hope this helps.
Scott.
 
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Rktpwrd

Comic Book Super Hero
Supporting Member
Feb 2, 2015
3,832
113
Calgary, Alberta, Canada
If you can, grab the driveshaft out of it when you grab the diff. Problem solved. That's what I did.
As far as the difference between the slip yokes from a TH200r4 to a TH200, I can't say. I went from a TH350C to a TH200r4. Maybe some other members can say yay or nay.
 

ssn696

Living in the Past
Supporting Member
Jul 19, 2009
5,391
113
Permanent Temporary
TH200C uses the same 27-spline slip yoke as the 200-4R, 700-R4, TH350 and TH250. The one that is different is the TH400.

I did just climbed under my coupe to measure the 8.5 yoke. It seems to use the same 534G U-joint as the 7.5, with the inner lock rings that fit into a groove in the caps. And I can back up that inch. That's about what it looks like I need to take off according to my current driveshaft. Just get the rear end of the driveshaft tube shortened and rewelded. I suggest new U-joints and a dynamic balance.
 
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tricrick84

Not-quite-so-new-guy
Aug 3, 2016
7
1
i bought a 84 cutlass 7.5 differential and tried to fit a 84 regal limited slip gear into it. the pinion started rubbing on the housing. would anybody know how to solve this problem?
 

tricrick84

Not-quite-so-new-guy
Aug 3, 2016
7
1
top one is the regal differential and the bottom one in the new one.
original regal diff.jpg
chrome cuttlas diff.jpg
 

pontiacgp

blank
Mar 31, 2006
29,280
113
Kitchener, Ontario
the lower rear is an 8.2 and that's why the pinion does not fit..and it will be wider than your G body rear
 
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