Axle and Hub replacement HELP on Vintage Trailers

I just replaced the axle on my '56 Dalton this week. Went from a 2" solid square Hadco to a 2 3/8" Dexter 3500lb. It took a little searching but I found one eventually at Trailerparts.com for $188. Note: Spring width is less important as you can get the seats welded on after you obtain the axle, or in some cases, you can specify the width when you order. I ordered mine unattached and brought both the new and old axles to a local trailer repair shop so they could exactly match them up.
Also, hub-face to hub-face is an important measurement and is how most axles (I found) are measured. It all made sense when I compared my old and new axles; the spindles were longer on the old axle, so the hub to hub would be different with the same overall length. You have to keep hub-face to hub-face very close or else you risk not fitting into your wheel wells.
I'm not sure if your's is straight or has a drop, but make sure to factor that in. Mine has a 4" drop which was much harder to find than a straight.
Finally, make sure to measure your springs (assuming you have leaf springs). I purchased a "standard" u-bolt kit and the bolts were too short. My trailer has something like a 4" spring stack which I have learned is "non-standard" and likely made from surplus WW2 jeep springs. Given that your's is a bit later, you may not have that problem, but it is something that did not occur to me until I was lying under the trailer.

Hope that was helpful...