This page describes how I built a heavy duty trailer from a military surplus trailer bed from M105A2 trailer. The subdirectories here offer pictures roughly consistent with project stages. The first shows the bed. The second shows the axle that I bought locally and then decided to not use. Then there are drawings. One directory offers pictures of the M105A2 trailer that I found on the web. The first thing I actually did was weld a adjustable eye rail to the tongue. Then I welded the frame, then I put on axle mounting brackets, on thick pads.
This homemade trailer has a bullet hole in a place which you would not expect to get damage from careless loading/unloading, see last picture.