I just won some 3.73 gears off Ebay for my 8.8 axle in my 2wd F150. I have a question though. On the 8.8's, I know they made a 28 and 31 spline model and was wondering if the gears I won, which I think are out of a mustang 8.8 will work in my 31 spline 8.8???


Also, will I pick up any performance?? I have the 4.2V6/auto supercab with 265's on ARE black steel wheels if that helps. Will I pick up some power I lost from going to larger tires? THanks for all the help guys.....

 

mike41005,
I was just cruzing the posts and saw your question.
The gears should be the same. The difference between the 31 and 28 spline is in the carrier that the ring gear bolts to. The ring gear should have 10 bolt holes in it.
Go to Ford and get new ring gear bolts. They are not expensive and have a lock-tight type coating on them to keep them from backing out.
My only question is why they were removed from the Mustang. I hope they are in good condition.
You will see a significant improvement in performance over the 308 gears.
Good luck and always have fun.

 

Thanks for the reply. SWEET truck by the way!!! I love that blower on the 4.6. Ive always thought about replacing my 4.2 with the 4.6 when the day comes(BOOM!!) Ive researched it a bit and found there are only minor differences that wouldnt be hard to change. After all, Ive switched a Toyota long bed 2wd Auto into a short bed Xtra cab 4wd 5spd. Thats my "buggy" I off road with. Heck, it's better than my Polaris...lol Anyways, I got the gears and they are NOT from a mustang, the guy on Ebay I got them from just deals in Mustang parts. They are indeed from/for an F150, so I'm in luck. He said the guy used them for about 5Kmiles and switched to 4.10's(with 235/70's) Can you say RPMS?? Anyways, I just hope I can tow my buggy Toy better with these. I also plan on adding some N2O...probably in the neighborhood of a 50-75 shot, just for the hills down south of Kentucky. Think that will kill my 4.2?? The motor has been apart and had a new Comp cam put in it along with new rings, etc. It has 87K and looked great. I can't wait to get my tuner to really take advantage of the cam, ported heads. Oh well, enough babbeling. Nice truck man....


Finally, do they make that grille for my 99?? that is awesome.....

 

Mike41005,
They make blowers for the 4.2

The grill is just a stock Steel Horse billet grill. The Blade Runner is off a 2001 Ford Taurus and you can get it from any Ford dealer.

Have fun.