I think I saw you did some research on that axle for a while, did you give up?
Any how few quick questions on tech.
450/550 had stock 35 spline outers. Is that why everyone sells 450 unit bearings, All they do is redrill stud patter.
450/550 are longer on each side by one inch?
The knuckles have bigger brakes with a bigger caliper mounting locations
450/550 have the bigger metric lug pattern than F350, which would be good for having more meat on hub flange for redrilling
450/550 all have dana 60 HP
How much for shipping 84104