These pioneer trailers are not on 416 frames but the larger m101 frames,, they just have a much much lighter box/bed on them instead of the extremely heavy dump bed of the m101.. The only thing that keeps any real weight on the pioneer frame is the big axle.. Some had the 3/4 t hummer bolt pattern axles and some had the 5 lug axles.. The newer ones had a flat area of the roof, and the older ones did not.. Most had a 6' box on an 8' frame. This also helped keep the weight down. They also did not have the double spring packs and huge landing leg wheel as some of the 101's did.. For more history on these check out the g503.org.. They make great off-road trailers and tow very well.. the weight is right in line.. I've been trying to find one of these near north east PA,, but haven't yet.. Good find.. drop in a good 3500# axle with a matching hub pattern to your tow rig and your all set..