3.73 or 4.10's

[86vert]

:pI know there is a thread already on this same subject. I have some questions for my 86. If I choose 4.10's will I need to do anything else to the rear? Should I have it rebuilt ie new bearings and such? If so is there a kit out there that is better then others. I am leaning towards the 4.10s since this will be a weekend driver only. Another thing, will the rear hum at all. My brother had a 92 with 4.10s and a 5speed and it would hum on the highway around 60-65 mph and up. oh and I guess i should let you know it is an aod also with a light B&M shift kit and 2200 stall. any suggestions comments would be much appreciated i will be buying gears at the end of the month. Thanks

[Notch93]

If your only changing the gears, and not the differential. Then I would have them change out (replace) the clutches in the differential also, why your in there.

The whine your brothers car had, was from the gears not being properly installed.:yes1:

[SVTSkip]

Vert + AOD = no contest, 4.10's all day long !!!

I'd do bearings/races/seals while you're in there, or at the very least have them on hand just in case. I'm with Notch93 on the noise. It sounds like the backlash wasn't set properly in your Brother's car contributing to the gear whine. I've had completely silent 4.30's, so it's not a ratio thing but rather how they're installed. I also agree that it's a good idea to upgrade the clutches in the diff while you're there. I like the FRPP gear sets as I've always gotten good service out of them. The only other thing you'll need is a 23 tooth speedo gear, gear lube, and a bottle of friction modifier along with the above mentioned parts and a new crush sleeve and pinion nut...

[Notch93]

The only other thing you'll need is a 23 tooth speedo gear

Make sure you get the black 23 tooth speedo gear, not the white one. The white ones get chewed up in the AOD's quick.

[86vert]

thanks for the info. hopefully i will have her done by mustang week. I have a lot of projects around my house to do before the stang gets any work done.