Don't forget to put some sort of easily seen mark on the driveshaft and count carefully; we just used a white paint mark. I recently had a friendly argument as to whether I had a 3.55 or a 3.50 ratio and we ended up jacking up one rear wheel (non-posi) and rotating the wheel 100 times before we were sure I have a 3.55 8" rear. I knew the 8" came in 3.55 gears but the garage guy is used to using 3.50 in the 9" rear so we had to check it out after the argument came to a certain level of stubborn disagreement.

Don Shillady
Retired Scientist/teen rodder