New Temp and Fuel Gauge Problem

The 12 volt supply to the limiter or regulator is the center spade. Could be that without the additional spade of the suppressor poked in that female connector you didn't have connection. The originally limiter did have heavy gauge metal spades to support its weight. I don't know what a aftermarket regulator is made of. I do know the female connectors are simply clipped into the circuit boards. If one was stretched a bit from having 2 spades in it....
Why the gauges read differently....I don't know. Crusty old gauges would have read a little low.