Voltage limiter

I used a $10 generic 5 VDC adjustable DC-DC converter from Amazon or ebay in my early-A's (voltage limiter inside fuel gage). Looked just like a Mopar-specific one that was sold on ebay for $35. The adjustment helps you tweak the fuel gage to read correctly at full or zero. To tweak both limits to correct, I had to add ~20 ohm resistors in parallel with the sender. There are mechanical zero and scale adjusters on the gages, which is via bending tabs, but intended only as a one-time factory calibration. Re temperature, if the gage holds steady while driving, that needle position would be the T-stat setpoint (usually 180 or 195 F), since it is controlling. I wouldn't get too hung up on whether that sits exactly at midpoint on the gage.