My 92 has an oil pressure gauge that reads "L ///". I went to the junkyard and pulled the gauge out of an 88 V6 Firebird that read "0-60". Got it all installed, needle sitting on the zero. When I turn the key on the gauge goes to 40, and when I start the car it pegs the gauge. Should I try swapping sending units, or just move the needle to "0" while the key is on but engine not running?
Thanks!

Sender and gauge are a matched package. Different senders have different resistor values that changes how the gauge will display. You need the correct sender for your gauge.

Thanks, it already has the 3 wire sender- but I'll get a new one. I see on Rock Auto they offer 2 different ones "light" and "gauge". I'm guessing I have the "light" one and I need the "gauge" one.

Also might want to confirm that gauge panel wiring and circuit board is the same. Nothing saying that it's the same on a 92 as the earlier cars. Maybe somebody else here will know.

There are no stops on those gauges. I would pull the needle off and put it back on with the key in run, engine off so you know where 0 is supposed to be. It may not read correct at pressure, but it will do like it is supposed to do and show you of any gross changes while the car is running