start with a wiring diagram, from the shop manual .... the temp sender is the ground, the other terminal would be switched power .... same for a fuel gauge, the sender is ground, other terminal is power .... amp gauge, one side goes to the voltage regulator, other side to the battery .... but again, check the wiring diagram or get a complete replacement harness

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics