Originally they were die molded (vulcanized) onto the running board. The Mercury stuff is mostly different that the Ford cars. Very little is interchangeable on the body. The Mercs were 4 inches longer begining in 41 and it's all in front of the firewall.
The running board part number is the for the 41 Ford and Mercury. That makes the covers the same P/N as the covers were not available from Ford separately.
Hi,
on the ford, merc. Runing boards. Some years ago i really lucked-out and found a pair of n.o.s. Boards. Not too long age i purchased another set yhat are in v.good condition, no rusr, etc.. If you need a pair, let me know.
By golly they do use the same part number. I notice that for the 41 Merc they list a set of mouldings and clips for the running boards. That must have been the only difference. The 39 & 40 Merc had their own part number seperate from Ford but begining in 41 they used some interchangeability. Sadly, not much else does.