Fuel Tank Sending Unit

Hello,
I have a M38A1 with an original M38A1 fuel tank under the seat. It has been converted to 12v electrical. I have two different 12v fuel gauges for it. When connected, both gauges show full when the tank is full and 5/8 tank when the tank is empty.
I would assume it's an original 24v sending unit and that's why the issue. However, all the catalogs show the original sending unit as having a 5 screw attachment for the M38A1. My tank has a 6 screw attachment. The top of the unit is 3.5" diameter.
Can anyone confirm the diameter of the CJ5 6 screw sending unit?
Thanks,
Ken

 

Voltage should not matter to the sending unit. At least on the CJs, it's a variable resistor to ground. As long as the resistance range matches your gauge, it will read the correct level. Can't help you with the sender top plate diameter though... though I would have removed and measured the resistance long ago. The M38A1 manual should tell you its resistance range, and the CJ TSM definitely will.

 

I think it's roughly 0-74 ohms. I did check it with an ohm meter but failed to write it down. I'll recheck next opportunity I get.