Ok a friend of mine is junking a 87 IROC. He says it has a stock 3.73 posi rear. But looking on this site, it looks like a stock posi rear would be a 3.23 correct me if I'm wrong). So my question is would it be worth it to swap my stock 3.42 non-posi rear for the 3.23 posi?
One more question...it is possible someone swapped in a 3.73 on his car...is there a way to tell by looking at the gearbox if its a 3.23 or a 3.73?

If anyone's wondering, my near future mods:
K&N drop-in filters w/ baffles removed
Catco cat converter
Dynomax 2.5" cat-back
MSD GM Blaster coil
MSD 8mm Heli-core wires
MSD 6A ignition

Got all this stuff, just gotta install it.



[This message has been edited by Mikes86SC (edited May 21, 2001).]

 

If it is a 2:73 posi I want it!
But anyway for performance reasons it would not be worth swaping rears from 3:42 to 2:73. There is a tag on limited slip rearends that states the gear ratio. If the tag is gone just pull the cover and get the numbers.
SSC

 

As far as I know, the 3.73/posi axle stopped in '85. When I was out hunting for the 3.73 axle, I was looking for only a couple years- 82-85. '84 Camaro H.O's got the 3.73/open/drum axle.. found a couple of those cars, but not the axle. I found my 3.73/posi/disc axle on an '84 trans am (engine code "G" for "I hit Gold!"), and they also came on the '84 Z28's.

So I think you're right... stock would be a 3.23. As for someone switching gears, that's a great possibility (I hope it's true for ya!), but there's no way to tell unless you drop the rear cover (as SSC said). I'd say it's worth smelling that stinky gear lube for it... a 3.73 posi would be great for ya! My axle, with the GM gears, had the ratio stamped on the ring gear (41:11). I counted the pinion teeth (11) and ring teeth (41) anyway... so if the gears in the back aren't stamped, just count teeth & divide.

Put a clothespin on your nose when you drop the cover... yuck.

------------------
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!