Wayne,

Jim Carter sells the little plugs that cover the holes in the running boards that are not used on a panel body truck (these are the small holes on the forward top edge of each running board that are used for attaching the running-board to pick-up-bed apron).

All 3100s are 1/2 ton (all 47-55 1/2 ton trucks are the same "short-bed" length).

Tim