There are drastic differences between a M101 and M105 trailer. Empty weight - 1450#s vs. 2750#s. The size of the bed - 5.5'x7'x15" vs 7'x9'x18" or so (IIRC). Then the frames are quite different in size, leafs, axles, tires, wheels, and the tongue.
If you really like the size of the bed, then I would look for a commercial flat or utility trailer to toss it on, or build a custom frame.
The M101 is a more pleasing trailer to be used behind today's smaller vehicles. The size is more acceptable. Swapping today's newer axles, wheels and tires makes a huge difference in weight reduction. Then same with suspension and tongue (lowering it requires work on the tongue stand).