JimsGT

+1 on the differential

My rear is noisy as hell, I had stock 3.31 changed to 3.73, then to 4.10, finally back to 3.31.... Every time seems no one could get the gears set up without the whine, and some prominent, nationally known shops who shall remain nameless couldn't get it right, and threw their hands up, "I'm baffled!"...3 different shops!

I'm sorry I ever messed with the gears, what a can of worms....

Like your car, maybe its the diff unit? IDK...

DJ Piner

A good friend suggested someone he knows that is really good at setting rear-ends up. Said he would probably do it for under $300.00 bucks. I have to furnish the parts. I can get everything I need from american muscle for about $430.00. Sounds a lot better than $1500 plus! Just undecided on which gear to use, 3.55 or 3.73. Pushing sixty years old I'm not in to racing anymore but would like to have a wee bit more get up and go. Do plan on taking a trip down to Key West so that means some interstate driving. Probably should go with a 3.55 gear?

ticopowell

Do you have a tuner?
http://www.americanmuscle.com/mustan...kits-0510.html
There is all their gear kits for your 08, unless you buy a tuner you can get them all for cheaper than $260

bstang14

I went with 3.90. I think it's a good balance. 4.10 too much for daily with 6 speed. 3.73 not enough. Imo. Word of caution. Purchase the Ford pinion seal. Do not use aftermarket. Ask me how I know.. Motive 3.90's have a very slight whine. Certainly not enough to notice with radio on or top down in my case. Nobody but me has ever noticed so it is definitely slight. Proper setup is the key. Any gearset not properly set up will whine or worse self destruct.

Simon1

This is what I would do.

my .02

Do not have a friend set up your rear end. They are guys with enough talent to do it, but most do not. Find a shop that is dedicated to only gears.

I used to have a Detroit locker in my car. Great for racing, crappy for the street. One day I got on the freeway and did a spirited run up to 135ish and afterwards, my rear end was howling. Took it to shop and all but one bolt on the ring gear was sheared off.

I replaced the diff with a gear driven LSD (no clutches to wear out), new ring and pinion, all new bearings and races, new axle seals (which I had just done), retained the OEM axle. All parts and labor at a shop that guarantees any gear they put in to be silent, less than $1300.

$1500 is too expensive. It should be closer to 600-700.

Clutches wear out and my gear driven LSD is quiet and smooth and holds 540 rwhp and sticky drag radials everyday I drive it.

Simon1

You will not notice a difference going from 3.31 to 3.55, you might notice going to a 3.73. Your mpg won't change much either.

bstang14

3.31 to 3.90 I lost less than 1 mpg and I attribute that to my right foot.