i have a friend that works at a ford dealer. they got a car with 12,000 miles complaining of a whine in the rear. they replaced the gears which were fine. anyways he will give me the gears for free. while i have the rear end apart should i swap out my 3.90's in favor of the 3.73's. i know i will lose some 1/4 speed, but i like to play on the roads a lot better! i just hate having to shift out of 4th gear at 115mph! i get my doors blown off every time i go to 5th gear. i was considering 3.55's but i'm not sure.