which factory rear end do i have?

**greatwhiteZ28** · 11-10-2006, 05:30 PM

i have a 02 z28 and i was told that i have a stock 3.73 im wondering which rear end i have cause when im cruizing at like 75-85 mph my tach is almost at 2700-3000 rpm . how can i tell help

**FantaZGuy28** · 11-10-2006, 06:28 PM

If you have an A4...then you would have higher gears than 323's because at 80mph im below 2500 RPM's. You might have 342's if the previous owner blew his rear end and found a M6 Fbody.

**Allen Wood** · 11-12-2006, 06:16 AM

I have a 3:73 gear along with an A4. At 60 MPH the RPM'S will be 3000 with the trans in D. Hope this helps.

**2001NBMZ28** · 11-12-2006, 06:29 AM

Look at the calculator at www.f-body.org/gears/

**Y2KPewterSS** · 11-12-2006, 08:36 AM

Originally Posted by greatwhiteZ28

i have a 02 z28 and i was told that i have a stock 3.73 im wondering which rear end i have cause when im cruizing at like 75-85 mph my tach is almost at 2700-3000 rpm . how can i tell help

GM didn't put 3:73 rearends in fbodies from the factory. If your car is a T-56(6 speed) transmission then you have a 3:42 rearend. If your car is a 4l60E(automatic) transmission then you have a 3:23 or 2:73 rearend. The calculator link listed above should determine for you which rearend you have. You could also look at the RPO codes on the driver side door and determine your gearing.