did all GN and TR, T-Types come with 10bolt 8.5" rear-end and posi-unit

[83BLACKHAWK]

I found this one selling on a site, and says it came out of a Grand National and says it does not have a posi, I myself think the rear end is 10bolt 7.5" rear-end out of a regular regal and he's selling it as a GN rear-end. I have asked him all kind of questions about it and he just says I don't know, I don't know

how can i tell the difference between the two rear ends

thanks for the help

 

[rodman99999]

They were all 10 bolt, but- posi was an option.

 

[WIKEDV6]

They were all 10 bolt, but- posi was an option.

Yep!!!!

 

[83BLACKHAWK]

the ad page has a lot of closeup pictures of the rear end, how can i tell that it is not a 10bolt 7.5" like i already have.

 

[83BLACKHAWK]

I am very interested in this rear end, I just been a Ford guy for the last seven years and I don't know much of GM stuff for the moment, I just don't want to buy over what I already got, so is it a 10bolt 8.5"

 

[wickedsixx]

Help for you

It looks like an 87 8.5 peg leg according to the code but here is a link so you can see for youself.
http://www.gnttype.org/numbers/axcodes.html
Shawn

 

[WIKEDV6]

It's an 8.5 all right. If it is off a Turbo Buick then it will have the 3.42 gear, If it is off an olds it will be 3.73.

HTH
Prasad

 

[mikestertwo]

It's definitley an 8.5 inch rear. Posi was an option on the turbo cars. The easiest way to tell the difference between the 7.5 and 8.5 is the 8.5 has a round bolt pattern on the cover. The 7.5 has an oval bolt pattern with it being flatter on the top and bottom of the cover.

I found this one selling on a site, and says it came out of a Grand National and says it does not have a posi, I myself think the rear end is 10bolt 7.5" rear-end out of a regular regal and he's selling it as a GN rear-end. I have asked him all kind of questions about it and he just says I don't know, I don't know

how can i tell the difference between the two rear ends

thanks for the help

 

[84BuickGNYorkPA]

Are you not sure if you have posi? I had a peg leg(non-posi) and all you need to do is buy the carrier(center section guts) and put that in the rear you got... That's what I did..

Chuck

 

[pacecarta]

on the subject of 8.5s

non posi would have alum drums
exception is GNX where there were alum drums on posi
posi came with steel drums
posi was an option on all regals except the 87 GN during the extended run (sept to dec 87) where it became std ( but price went up as well)

 

[MY3TTYPES]

on the subject of 8.5s

non posi would have alum drums
exception is GNX where there were alum drums on posi
posi came with steel drums
posi was an option on all regals except the 87 GN during the extended run (sept to dec 87) where it became std ( but price went up as well)

My 84 GN has factory posi 3.42 as well as aluminum drums so....

 

[84BuickGNYorkPA]

Paul, How do you know all this stuff, my 84 did not have posi, but it too had aluminum drums, like Paul said. When they where worn out I replaced them with steel drums, I was told that the aluminum drums tend to crack when you turn the hp up...

 

[Ormand]

I don't think that the aluminum drums were completely linked to the posi. There were other things involved that affected which drums were used. That's what I've read on these boards, anyway.

 

[rodman99999]

The aluminum drums(with a steel liner) have problems when the wheel cylinders have been upgraded(like to the S-10 manual brake pieces) and/or a front brake bypass valve is installed. The problems usually start if the drums have been turned more than once(takes too much liner out). Both mods put more hydraulic pressure to the rear brakes(better hold for boosted launches), and the aluminum can't handle it. Nothing to do with the HP or type of rear end. The other drums are cast iron with a steel liner, and the cast iron can take the added pressure better(if turned a couple times).

 

[wickedsixx]

8.5s were in 84-87 turbo cars and not the earlier carbed turbo cars. As far as gns and t-types are concerned.

 

[steve hughes]

Not all non posi cars had aluminum drums. My 86 was non posi with steel drums.

 

[bison]

I have or had (one was stolen in 97 )3 86's, 2 with the open diff when i got them and the 2 open ones had aluminum drums on them. The one that came with the limited slip (G 80) does not have aluminum drums. It may have had them when new but it didnt have them when i got it. Its safe for me to say the other 2 came with them from the factory. I have never noticed any particular reason why some came with or without them. Ive noticed a lot of 87's came with iron though and most 86 GN's had aluminum.