well its a 10.5" sterling axle. do u mean how do u figure out what gearing u have/

 

10.25- Pre-97 F250 & F350

10.5- All single rear wheel Superdutys

Dana 80- All dual rear wheeled F350s & the older (80-90) Medium duty Superdutys (F450)

Dana 110- All 99+ F450 & F550 Superdutys

There should be a tag on your diff cover that will say 4.10 or 3.73 gears. Chances are it's a 3.73 rearend. Why do you want to regear it?

 

Dana 110- All 99+ F450 & F550 Superdutys

Incorrect,
Our 99 and 00 F-450s are Dana 80s and our 02 F-550 is the Dana 135. Not sure what model year they switched to the 110s, but I'm guessing 05.

Looking at my 04 owner's manual it lists 80 for the 450 and 135 for the 550 as well.....so I guess the 04 is a Dana 80 too.

 

I have 3.55's they are the best thing ever. My guess is he wants the fuel milage and the 110+ mph speed the higher rears will get you.


I would rock a 2wd w/ some 3.08s in a heartbeat

 

I have a 99.5 f250 2wd 6 speed how can I tell which rear end I have?

Drop your trousers, back up to a mirror, and look over your shoulder. That method should tell you pretty definitively what kind of rear end you have.

 

LMAO :stupid:

If it's a SRW you have a Sterling 10.50, dually would be DANA 80

 

Dan-O beat me to it, he's on it!!!!