You can shave a lot of weight off those by changing the axles and wheels. I have an M101a with 5.5 axles with tires and wheels to match the Bronco. I still need to change some things out and make it even lighter, but the axle swap alone has to be 100# weight savings.
M101s are Vietnam era to later and much cheaper than the M1102. I think those are slightly bigger and beds are aluminum. I found my m101 on craigslist for $300, but the bed is a little rusty.