The factory connectors are referred to as Packard connectors or shell connectors.
I recently saw a post somewhere...I think it was on the 5-ton Facebook page(?) where someone showed a military headlight fixture that used replaceable H4 bulbs. These could be used in any HMMWV, M809, 939, M44 etc. series truck.
Crud...if I can find the post again, I'll copy it and put it here. It was a comparison of JW Speaker LED's, stock bulbs and the H4 unit.