Hooked a AA battery between the temp sender lead and bat ground?? Ummm, no. Jumper the temp sender lead to ground and turn on ignition, check for needle movement. When the voltage limiter for the gauges goes poof it can fry the gauges but like I said, don't often see that. A simple ohm meter across the gauge leads should tell you.

This bit is easier if you have the wiring diagram but ya can do it blind if ya really have to. Pull all the gauges out of the carrier, figure out which clip on each one is ground. Run an ohm meter between the other clip and the sender lead. There's a connector at the gauge cluster that can cause issues but usually doesn't. Same with the bulkhead disco. In the case of early 76 build there's another disconnect on the passenger side wheel house.

The Rallye dash is kinda nice to have from a rarity standpoint - if you can find a tach with the needle still attached. Used to be a pretty cheap score at swap meets and bolts right in. I find the gas gauge hard to read in part because it has about 1/3 the sweep of the regular gauge. I might still have most of one stashed away and more than likely have a lower bezel. Lemme know if ya want me to dig.