Dave, this page has a lot of useful info: Mr.N's Dana Articles to Include 44, 60 information.
Specifically this page: Dana 44 Solid Front Axle: Reverse Spiral and Standard Housing info..

The front D44 should be a High Pinion one. All F100 front axles from 1966+ had D44HP's to my knowledge. This means that the pinion and ring gear are cut in the opposite direction and aren't transferable to the rear axle.