Isn't Macs a Ford supplier?
Yes, you're right. The sender came from LMC - at the same time I was working on a '48 Ford F3 and had a nasty time of it with Macs' stuff not fitting and working right.
Autometer offers 3 different fuel level ranges, the one I chose was 0-30ohm and it tested proper with the sending unit in hand operating thru its' range. I would've bought the sending unit from autometer but they don't offer one for that range.
Keep the thoughts coming, they are helping.