I have one M101A1 that was converted to a generator/light trailer. It had the gerry can mounts on the fenders, a hole in the bed for the fuel line, and a M37 style gas tank mounted under the bed. It also had racks mounted for the light poles...
Most of my cargo M101/M101A1's have been lacking in extra holes... A few have had one drilled in each corner to help drain water, and a few have evidence of having a spare tire mount bolted to the outside of the front bed wall. Sadly, none of them has come with any spare stuff mounted to them, but I have had some with loose gear tossed in (one Craigslist find came with a wiffle tree and some chains...).
My M116 genset trailer came with the gerry can mounts, pole brackets, tarp clips, and the tool box (loaded) along with the tarp... and the generator...