4.10's
 

Would I be o.k. to run 4.10's in an A4 10bolt? Or should I go with 3.73's?

I'd go with 3.73s if its a daily driver. If its a track only car I'd say 4.10s or if you don't mind about shitty gas mileage on a daily driver. I've been told not to yse more than 3.73s though.

A4 - 3.73's
M6 - 4.10 or 4.30's if you can find the 4.30.

4.10s in my auto and love them!!!

What are your rpm's at 60 in overdrive?

I'd guess 'bout 2200rpm.

ugh..i always forget what 60 mph is
80 is right at 3000rpms
60 i believe is 2300
50 is definitely 2000rpms
hope this helps

If you don't mind the gas, go with the 4.10's. I have them on my car and the gas gets expensive. I'm thinking about changing to 3.73's after i break them. One thing i don't like about 4.10's is how revved up the car is on the expressway.