78-79 f250's had the best dana44's high pinion, flat top knuckles and two piston calipers. I believe some 76-77's had the same disk brakes but low pinion. should share same frame width as the spring perches, but leaf-spring width may be diffrent. The late model axles have wide spring perches so they are incompatible.
This place sells a kit for the large closed knuckle 8 lug dana 44
4x4 Front Differential Disc Brake Kits