UNICOM tub 1942 MB?????

[ybuszone]

I just picked up a 1942 MB so says the title. On the tub behind the drives seat it has a tag rivited to the fender well. It has UNICOM on the top and NO. _ _ _ _ _. Does anyone know what this means or how to look up the number (dont have it on me right now). It has no tailgate.