So I was going to get a 3.73 rear gears for my car. I finaly took off the rear cover and found out I have 3.23's already it stamped (well can't remember the. 4 number but I divided them and it came out to like 3.21 or something around there) and 7 5/8 ring gear. I want to use this car as street/strip. So give me your opion do I A. Get new 3.73's or b. just get a posi unit for my 3.23's.

Thanks Tom

 

42 : 13 = 3.23 (RPO GU5). You should have a 7.5 rear unless the rear end has been swapped.

JamesC

 

Choosing a ratio has to match the rpm range of the engine, and the usage of the car. If you're doing a city build with a 5500+ rpm cam and good aftermarket heads, do the 3.73s. If it's a highway cruiser for long trips, with a torque cam and ported stock heads, then keep the 3.23s.

 

The cam I have makes power up to 6000 rpm. The heads are GM remaned with stage 1 ported with 202 valves. I will be doing mostly city driving.