do you have any pictures?
77.5-79 Ford Dana 60 fronts will have 35 spline inners, 30 spline outters. The inners will neck down unless they've been replaced with Spicer replacement shafts.
Ford didn't make a F350 4x4 until '79, so either it's the typical "I got a 60 so it must be a F350" thinking since Ford did put 60 fronts in some F250s with a high enough GVWR, or it was a conversion with god only knows what parts.
If it is reverse cut, & open knuckle it'll be a 35/30 combo though.. I can't even concieve how you could put a D44 shaft into this axle... maybe put a 30 spline side gear in, but that'd only help on the inner axle, you'd still need to do something custom for the hub. The early 77 & earlier axles were D60 centers, with 30 spline inners & 19 spline outters, & had the same small u-joint as the D44. They were also all closed knuckle & drum brakes.