I am not sure what it is for sure. I think its an old F1 maybe Econoline. Hopefully someone here can pin point it. Spring center to center measure about 32 3/8 inches. 2751 is stamped on the wheel cylinder. That number crosses to late 60s-early 80s f250, f350, econoline. I don't know if that identifies the axle though. I am hoping I can use these brakes on my 32 Tudor. Haven't measured for any of that yet though. Thanks!
I agree, the spindles look like F1/F100, and I can't tell if the axle is straight or dips in the middle. This helped me ID my F1 axle: http://www.droppedaxles.com/FORD_AXLES.html#TXTOBJ7D814314E192261
Dip in the middle...clamp style pitman arm with a ball end...2 bolt on steering arms, unlike the 48-52 F1 that had a bolt on arm only on the left spindle. Given those clues I'd say 53-56 F100. 57 and up F100 used a pitman arm with a modern tierod end.