A lot of us had that same folding shelf back before giant tool boxes became the norm. The color looks the same because almost everyone in the shop had a red tool box and the difference in shade between New Britain, Snap On, etc has been lost to the ages. I used to work out of a NB top, Snap On middle and a Craftsman roller with that side shelf and except for the age staining the paint colors could have been identical. I don't remember where I got that folding shelf but have a thin memory of buying it from the Sears store, but it could just have easily come off of the tool truck which at that time was an independent guy carrying mostly SK and Cornwell tools. I think I know where I stored it so I'll check for a manufacturer mark. As was pointed out, the older cabs had a lip that would support this shelf and the newer ones don't so I haven't looked at mine in years.
Was your shelf originally part of the roller cabinet? No. Was it purchased at the same time and from the same seller as the roller? Quite possibly. Was it added on later when he started to outgrow the cabinet? Very likely. Did it cease to be folded up and down and gain it's own permanent collection of tools after a couple of months? Mine did!
Joe
