It sounds like what you are saying is that 53-59 3100 are the same so then they would be the same as 49-54 Passenger car? Because the passenger car hubs and brakes will go on the 53 3100 spindle from what I understand, changing it to 5 lug. The 49-54 passenger car spindles will fit on a 47-52 3100 so you can change it over to 5 lug passenger car pattern.
I have a set of each, one set on a passenger car front suspension assy, one set I got with an axle (don't know the year though) AD 3100 (which has a shorter axle than the 55-59 3100) and then the pair I got from the 55-59 Speedway dropped axle I just sold. The passenger car ones are still on the front so I can't do anything with them but the others I could throw a few measurements on them, they are relatively easy to get to in my "wrecking yard".
Brian