10.25 rear (Sterling) and I believe that'll be a D60. However, the Super Duty Dana 60's from '99-current have a different (less desirable--8 on 170mm) bolt pattern than the standard 8 lug (8 on 6.5").
Why F*rd decided 170mm is cooler than 165mm is beyond my comprehension. Probably the same guy that thought a 7 lug light duty 3/4 ton was a good idea?
They should be fine, they just suck to drop 300 bucks a piece when they go out. But between that the wheel bolt pattern and ball joints, it's hard to put money into them
F250? Dana 50 front I think. 10.5" Sterling rear. Dana 50 is basically D44 r&p, 60 outers, right? Not bad, really, if you think about what usually breaks on a front axle, it's not the r&p. There's a useless thread on POR about it.
Harper is correct. Look for a casting mark on the housing or just measure the pinion nut. Dana 60 will the larger 1 5/16". But 06 will be a 60 with coils and radius arms so plenty of room to fit coils and a control arm mount. Also the ford sticker on it will have 248 on it which means 248mm=9.75" ring gear.