F250 Diff pictures by islandfd3s - Photobucket

1999 F250 7.3 SRW 2WD Auto Longbox

3.73 gears according to the ring gear.

Wanting to order a rebuild kit, ring and pinion and new clutches for the posi and I want to make sure I get the right stuff the first time! That diff went 350,000 miles but now it's getting annoyingly whiny. It's been making noise for the last 100,000 miles, but only recently have I driven it at high speed long enough for it to bother me.

I had thought about replacing the truck with a newer, lower mileage 4x4 but just can't find any and mine still has no rust so I guess I'll just keep fixin it, maybe swap it to 4x4 this fall.

 

All superdutys come with a Sterling 10.5 rear axle...


Clarify...

ALL single rear wheel F-250 and F350's...

 

Not all 99s have a 10.5 ring gear. Some have a 10.25.

See this THREAD.

 

further info: See those pics in the first post if you missed the link.

My truck has rear discs, calipers on opposite sides (ones on the front, other on the rear)
It's a crew cab.
I think i have the "heavy" brakes.

I just read somewhere that the parts are interchangable anyways as long as you buy 100% of the parts - eg if I have 10.5 now and buy a 10.25" ring and pinion and bearings it'll all fit in and work. Is that the case?


Where would I find this tag with the numbers? I didn't see one anywhere when I pulled the cover.

 

The tag should have been held by one of the diff cover bolts.

To determine if you have limited slip get both rear wheels off the ground. Turn one wheel and if the other wheel turns in the opposite direction it is and open diff and not LS. If the other wheel turns in the same direction it is an LS diff. This only applies if the LS is functioning properly.

The caliper positions tell me you have an E99 or a late 99 with E99 suspension. What is the Manufacture date on the door sticker? If it is before December 98 it is and E99 build. If it is Jan 99 it is a late 99. Ig it is Dec 98 it could be either. Some 99s built up to May 99 can have E99 suspension and brakes. There can always be exceptions.

If the 10.25 and the 10.50 ring gears both mesh with the same pinion gear than they are interchangeable, which I believe is the case.

 

Truck was painted, all my stickers are MIA

If you look at the pics you can see that it's an LSD. The clutches are worn out too and that's something that I would love to fix, 1WD diesel trucks get stuck real easy!