Goose wroteHmmmm.. I haven't seen a lot of short bed stepside j-10's but that one looks like a chevy box..69-70?? still a good looking truck, wish I had about 2000 cash..!
That bed is a Sportside bed that came out in 1980, prior to that they were the same bed with different (Willys) fenders and frame covers and were called Thriftside beds.
Early (Kaiser) Thriftside beds were available in 7' on 120" wheel base & 8' on 126" wheel base, AMC beds were limited to 7' on 120" wheel base.