The Sierra tubs have the same bottom measurements as the M416 (41" X 72"). I am not sure but I thought the WW2 trailers were about 2" narrower than the M416. The M416 I have looks great from a distance because of all the bondo in it, but I now want a tailgate and a lid so I can mount a RTT. After looking at how much work to fix my tub so it could be square enough for a lid and tailgate, the Sierra tub looks like a good option. Some mounting tabs on the sides with the angle iron mounts welded to the bottom of their tub looks like all that would be needed to mount the tub providing that the 43 year old MN416 frame is straight.