better rear diff of the 2
better rear diff of the 2 I'm helping my son build a 99 z28. i haven't pulled the cover yet but something is wrong in the diff. However I do have 2 other rear diffs ready to go. One is out of a 93 Trans Am WS6 6 speed car and the other out of a 99 Camaro SS SLP auto car. I know they are basically the same but was wondering if one might be better then the other or are they basically the same?
Joined: Nov 2001
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From: Schiller Park, ILL Member: #317
A couple of things here... first, there was no "WS6" Trans Am for 1993; this package was not introduced as a trim level on 4th gen F-body until 1996.
Second, the LSD for the earlier 4th gens was an Auburn unit, but in 1999 GM switched to a Torsen LSD. So the '99 SS would have a Torsen, UNLESS it was ordered with the optional Auburn upgrade from SLP (only optional on SS/Firehawk). All else being equal, I would always choose the Auburn over the Torsen, but as these are *used* units they are likely not equal in condition. So you'll probably get the most life out of the one that has the lowest miles and/or has seen the least abusive usage. I've had both versions (Auburn and Torsen) across several different 4th gen F-bodies, and the Auburn just operates better IMO (smoother engagement, no chatter).
Are you swapping gears as well? The '99 SS auto would have come with a mandatory 3.23 gear option. I seem to recall the '93 M6 cars also coming with a 3.23 (vs. the later 3.42 gears for manual cars), but I could be mistaken on that.
Second, the LSD for the earlier 4th gens was an Auburn unit, but in 1999 GM switched to a Torsen LSD. So the '99 SS would have a Torsen, UNLESS it was ordered with the optional Auburn upgrade from SLP (only optional on SS/Firehawk). All else being equal, I would always choose the Auburn over the Torsen, but as these are *used* units they are likely not equal in condition. So you'll probably get the most life out of the one that has the lowest miles and/or has seen the least abusive usage. I've had both versions (Auburn and Torsen) across several different 4th gen F-bodies, and the Auburn just operates better IMO (smoother engagement, no chatter).
Are you swapping gears as well? The '99 SS auto would have come with a mandatory 3.23 gear option. I seem to recall the '93 M6 cars also coming with a 3.23 (vs. the later 3.42 gears for manual cars), but I could be mistaken on that.
^^^ as above plus TC vs non-TC. does the current 99 Z28 have TC ? the 93 definitely would not have it, the 99SS could. No compatabilty in the systems and would cause warning dash lights on.
You are also correct that no 3.42 rear gear was available in '93, the M6 cars got the 3.23 gear, A4 cars got either the 2.73 or 3.23.
Last edited by JohnnyBs98WS6Rag; Oct 15, 2021 at 08:12 AM.
Joined: Nov 2001
Posts: 34,629
Likes: 2,550
From: Schiller Park, ILL Member: #317
In fact, my '89 Formula 350 also included the "WS6" RPO. But, again, this was not an outwardly badged (other than the center caps) package as we see with the 1996-'02 examples, so folks don't typically refer to these as "WS6" cars either. I do seem to recall there being two levels of Trans Am in the early 4th gen years though...Trans Am and Trans Am GT (none were actually called a "WS6" nor badged as WS6 or GT). Other than the raised deck spoiler (which I think was RPO T43), I don't know what else the "GT" package consisted of.
A couple of things here... first, there was no "WS6" Trans Am for 1993; this package was not introduced as a trim level on 4th gen F-body until 1996.
Second, the LSD for the earlier 4th gens was an Auburn unit, but in 1999 GM switched to a Torsen LSD. So the '99 SS would have a Torsen, UNLESS it was ordered with the optional Auburn upgrade from SLP (only optional on SS/Firehawk). All else being equal, I would always choose the Auburn over the Torsen, but as these are *used* units they are likely not equal in condition. So you'll probably get the most life out of the one that has the lowest miles and/or has seen the least abusive usage. I've had both versions (Auburn and Torsen) across several different 4th gen F-bodies, and the Auburn just operates better IMO (smoother engagement, no chatter).
Are you swapping gears as well? The '99 SS auto would have come with a mandatory 3.23 gear option. I seem to recall the '93 M6 cars also coming with a 3.23 (vs. the later 3.42 gears for manual cars), but I could be mistaken on that.
Second, the LSD for the earlier 4th gens was an Auburn unit, but in 1999 GM switched to a Torsen LSD. So the '99 SS would have a Torsen, UNLESS it was ordered with the optional Auburn upgrade from SLP (only optional on SS/Firehawk). All else being equal, I would always choose the Auburn over the Torsen, but as these are *used* units they are likely not equal in condition. So you'll probably get the most life out of the one that has the lowest miles and/or has seen the least abusive usage. I've had both versions (Auburn and Torsen) across several different 4th gen F-bodies, and the Auburn just operates better IMO (smoother engagement, no chatter).
Are you swapping gears as well? The '99 SS auto would have come with a mandatory 3.23 gear option. I seem to recall the '93 M6 cars also coming with a 3.23 (vs. the later 3.42 gears for manual cars), but I could be mistaken on that.
