change in gas and temp gauges

for years my temp gauge has worked well, verified with infrared sensor at the thermostat housing. At 180 to 190 degrees it sat 1/3 of the way into the bracketed part of the gauge. Once up to temp, if you turned the car off and came back 20 minutes later the gauge read 2/3 or a bit more and when you stared it soon was back down where it belonged.

My gas gauge has always been off showing 3/4 tank when full, which is just fine as it keeps me from tempting fate in terms of running out of gas.

Suddenly, when up to temp the gauge reads at the bottom bracketed line, but sensor tells me it is 180-190. When you turn the car off and let it get hot, it never moves off the lower mark.

At The Same Time, gas gauge reads 1/8 tank when full.

My tentative diagnosis is that the voltage limiter has failed / is failing...

Car has a four year old M&H dash harness and a 6 year old under hood harness. Original Gauges and a transistorized voltage limiter.

What say the electrical gurus???