Reading set up shop in '55. But I remember most guys making their own from wood, side boxes and saddle, into late-70s, including me.
Man, just yesterday I come up behind this heavy equipment mechanics truck at a stop. Peterbilt utility body all set-up, red as red can get and clean as a whistle. First I notices the tow chain hoops with perfect paint. Then the shiny black snap down tonneau. That's when I notice the paper temp tag. Brand spanking new I want it I want it truck. This is a roads contractor nearby who has yet another pretty fleet of all red trucks. This guy is doing well, obviously. All his stuff is either a Mack or Peterbilt and looking fresh all the time. His low-boy even has red fiberglass tail dragger fenders (that's what I call them), which seem more show than go for the application. If it were me they'd be metail with more ground clearance.
https://www.google.com/search?q=M+T+...w=1138&bih=526