Depends on which connection is bad, and where it went bad. If it's something behind the gauge it's easy. If it's a bad sender, or bad wiring near the sender, then you have to drop the tank to access it.
I just don't remember on our gauges if they go to empty or full when the ground is disconnected.
My oil line fix
My 100k stopped odometer fix
Brace for impact, I'm in a "modifying mood". Massive thread count inbound.