Originally Posted by Bigbob
I have never understood the idea behind using a vehicle differential for a trailer axle. Not that there is anything majorly wrong with it and to each his own and all that rot, but I figure if a differential is cheap enough to get from a junk yard it probably is indeed junk.
Usually you take the entire back end of the pickup truck it was taken from, including frame, springs, suspension, etc, and modify the front for a tongue. I couldn't imagine building a trailer from scratch around a vehicle axle, but I've used trailers made from the salvaged back end of a pickup truck, and they worked fine.