seansod

Alright I am feeling pretty stupid but what rearend do I have. The car is a 74 manual with a wide ratio muncie 3.08 I think. Do I have a 10 bolt 7.5 or 8.5?

Thanks
Tony

gerry72

You'll have to read and post the differential code that is on the bottom of the carrier housing for anyone to say what gears you have. Put the car in the air, get a scrub brush and some cleaner and attack the very bottom of the housing. The embossed code is very shallow and is hard to read even when clean. The code method only indicates what gears were factory installed in that housing, not necessarily what's in there now. Alternatively, you can jack the rear up to get both wheels off the ground, put a mark on a tire and a mark on the rear yoke. You rotate the tire one revolution and have a friend count the driveshaft revolutions. If it's about three driveshaft revs, then it's a 3.08. It probably is a 3.08 but could be something else since there were optional ratios.

The 63-79 Corvette IRS differential is unique and shares no parts in common, including the ring and pinion set, with other GM differentials. The actual ring gear diameter is 8 3/8".

IETEK

4th gear 1:1 RATIO 75 mph your tach will read you rear end gear ratio e.g. 3:70 rear ratio tach reads 3700 rpm


IETEK :cool: