Tom Brunas

ok have a 99 z and not sure what size rearend since sticker on door is gone. how do I check this?

HCI2000SS

iTrader: (2)

Stick or auto?

Tom Brunas

it is auto

FirstYrLS1Z

iTrader: (4)

what size rearend or gear ratio ?
door sticker indicates ratio.
rearend size in 10 bolt 7.625"(same as 7.5",parts are same/interchangeable).
ratios;M6-3.42:A4-2.73 or 3.23. 2.73-steel driveshaft 3.23-aluminum driveshaft 2.73-gear selector can't be put into 1st(blocked by a factory installed plastic tab.
post up what you determine/find.

Tom Brunas

need to know gear ratio, feels like 273, but want to make sure before I hunt for 323 or higher

FirstYrLS1Z

iTrader: (4)

@60 mph in 4th with convertor locked 2.73=1500rpm 3.23=1865rpm. those are true rpm's,dash tach typically indicates 150-200 rpm higher than actual.

Tom Brunas

need to find gear ratio

Tom Brunas

ok think its a 273 then, @ 70 im at like 1800 rpm
ty for your help.

now you have any leads on finding a 323 or higher? lol

FirstYrLS1Z

iTrader: (4)

a 3.23 complete rearend ? if so,what's the 'channel',3 channel is ABS only,4 channel is ABS & TC ? your location ?

Tom Brunas

not sure what channel, and im in mich. yes complete rearend I think would be best

FirstYrLS1Z

iTrader: (4)

you NEED to know which channel your vehicle has to get the proper bolt-in rear !!!
3 channel-1 sensor on top of rearend,4 channel-1 sensor at each axle backing plate.

Tom Brunas

ok will find that out, any leads when I figure what channel im looking for
?

FirstYrLS1Z

iTrader: (4)

need to know 'channel' before you start looking.
if yours is 4 channel,a 3 channel rear can be converted to 4 channel by using your current axles & backing plates into the 3 channel rear to convert it into a 4 channel. if yours is 3 channel,a 4 channel rear cannot be converted into a 3 channel and you'd have to find a 3 channel.

Tom Brunas

ok ill get back to you in a couple days, ty

Tom Brunas

ok looks like I have sensors on both brake back plates, and a steel drive shaft

FirstYrLS1Z

iTrader: (4)

Saw your pm,just got home from Cedar Point.
OK,you got a 4 channel vehicle and you want a ready-to-bolt-in rearend of 3.23 or higher. Your options are 3.23 and 3.42. The probability of finding a 3.73 is slim to zero. 3.42 rear would be out of a 6 speed and 6 speeds abuse our little 10 bolts so your best option is a 3.23 out of an A4.
A 3.23 3 channel rear is usable but the ready to bolt in aspect would be gone as you would have to interchange axles and backing plates. Most/many rearends that are pulled to replace by 12bolt/9"/S60 have their backing plates gone as they are needed for the upgraded rearend.
Locally to you in Michigan would be a priority as nobody wants to package up a rear for shipping.
Your 99 would have a Torsen(99-02)posi,98s' would have an Auburn posi. Some 98-02 f-bods had optional Eaton posi installed at SLP.
Search the 'parts for sale' classifieds in this site for 'rearend'.

check the 'speed shops' in your area,when they upgrade a car to 12bolt/9",the complete taken-out rear is typically discarded to a 'scrap pile'.