In reading through these responses, it looks like there's some confusion about what you mean by "long bed." To be technically correct, there were actually three pickup beds offered -- 77" (half ton), 87" (3/4 ton), and 108" (1-1/2 ton). The 108" beds are pretty rare and few people know they even existed, so they refer to the 87" as a long bed.
I'm almost certain that the 77" and 87" inch beds were unchanged from 40-46. I know the beds were narrower in 39, but I'm not sure about pre-39. In all cases, though, the tailgates, front panels, support rails, etc. were common between 1/2 and 3/4 ton models--the only difference being the length of the bedsides, wood, etc.
If you're interested in the 1-1/2 ton (108") beds, well these were a totally different animal. They share no parts at all with their little brothers. The "bed side curl" is actually triangular in cross section, rather than round like the small beds. This bed was unchanged from about 1932 (I think) to 1946. (There was a 9' bed offered in 47, but it was a different design.) If this is the bed you're interested in, email me directly, and I can get you all the information you need, including the chains.
Bob
