A Rockwell F106 is commonly known as a FDS75, FDS stands for front drive steer there are three different variations of an f-106 front axle 2 of the main versions have drum brakes and run smaller king pins with taper roller bearings, the axle shafts found in these can be 2 different versions, one has 19 spline 1.75" inner shafts, the other has 34 spline, both run a small 1-1/4 outer stub shaft

The 3rd version came with disc brakes and rims 1.75" 34 splines inner and outer; it also runs a 1.75" king pin with a bushing not a bearing

F106 axles in a normal configuration are a low pinion design, most run a 1480 yoke

Wheel bolt pattern is the same as a 2.5 Ton Rockwell

Front

Weight front with brakes 835lb

W/O brakes 681lb

Rear

Weight front with brakes 545lb

W/O brakes 451lb

F106 axles do not have the common spindle and knuckle issues 2.5 Ton Rockwell’s do, the spindles are held on by larger 9/16 bolts and the knuckles seem to be more robust

F106 axles are commonly used in low slung light weight race trucks, and because of their light weight and high strength they are also popular in pulling trucks