Oil pressure gauge not working on 71 Demon rally guages

67Dart273 said
The quick check is to ground the sender wire, then turn on the key for NO LONGER than necessary, the gauge should immediately head to "full"

This will at least split the problem

I did this and the gauge went to full so I will replace the sending unit. Does anyone have tips on replacing the sending unit? It looks hard to get at so I will remove the air cleaner.