whats the differnce between the gears in 1/4 mile times and gas mileage? thanks.

Really the difference in a quarter mile will only be fractions of a seconds...anywhere from .2 up to a second (also depends on the driver haha)

Gas milage will stay about the same...not to much of a change.

It can increase your hp and torque numbers...It just all depends on the cars tranny and engine performance.

But all in all id go with the 3.73's....

Its currently what im looking for my car...

The difference is night and day. That being said you need a motor that will make use of the gear. If your gonna stay rocking the V6 I wouldnt worry about dumping money into the rear end.

I went from 3.23 to 3.73 and it is a noticable difference in acceleration. Not "night and day", but that is probably due to the paper weight under the hood.
I never record mpg with my car, so I couldn't tell ya about that. Highway rpms are about 2000 at 60 mph.