Forgot to ask if car is 6 volt. . Is the tank a plastic replacement and if so, how is the sender grounded?

Roberts Motor Parts had sending units at one time; some 1 wire and some 2 wire

Tanks.com

Not sure, but I think the passenger cars for that year used a two wire sender. Perhaps your truck needs a two wire sender too. . . If so, then none of the modern one wire sending units will work. Might want to check with a vintage Mopar parts specialist to see if one of them has a two wire sender that will bolt into the SAE fuel flange that your new tank probably uses.

I got a fuel tank in the sending unit from tanks I don't believe they sent me the right ohms a 73-10 can someone tell me what Ohms sending unit I might need ? Thanks