I put a meter on my 1973 gauge and it shows about 60 ohms full and stops at about 180 on the empty side, even though the float drops further. I pulled a sender out of a 1974 tank, and its numbers are a lot closer to yours for the '73. I guess these things wear over time.

I had a look at my '73 sender and I can't find any part numbers on it anywhere. There's the remains of what might be a painted"OK" on the top near the connection. By contrast, the '74 sender had easily visible numbers on it.

Re the tank, at this stage I'm not sure what to do. I'm more than tempted to POR15 the '73 tank because I haven't had any luck sourcing a replacement '73 tank. But the earlier one has no rust anywhere, which tempts me to weld the '73 "hole" to it and use that sender. What do you think is better?

Regards
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JohnH, Sydney, Australia