I'd have to figure the running board tool box is just an owners common addition to the typical work truck of the 40's and 50's. I have to admit it's a natural place for a tool box. I've also seen gas cans,chain boxes and handyman jacks mounted there.(also a bucket of fence staples,once.) I'd put one on my '57 if it had running boards,but since it has a fleetside bed I'm stuck with a crossbed box and a couple of smaller fenderwell boxes.
I did score a BIG gangbox that now resides on my 62's flatbed. (still not enough room)
Speed
