I am not sure of the exact timeline, but it seems NMW started out in Hackensack, NJ, then by 1973 (for sure, but maybe earlier) they moved to Elmwood Park, NJ, and then sometime later they have listed Raritan, NJ.
I've only seen the barrery box on later literature, so my guess it is was later 1970's at best and maybe 1980's.
Below is a insert found in some NOS NMW drive shaft loop's me and my pop bought off ebay. Tommy, you can see the weight box there, but I'll grab a pic of the box over at Plowman's house.
Here is a cell phone pic from a few years back. I bought some Cragar wheels from a fellow and saw he had an NMW cherry picker.
Notice the address. I wonder which address was the one that the pallets of tow tabs and such were sold from? Raritan?