IVR- What does it look like?

I have a 64 Dart GT and my fuel gauge and temp gauge were bouncing up and down the other day, then just went to zero and stopped working at all. What should I be looking for? I have been reading a few posts and there is a lot of talk of bad IVR. What does it even look like, so I can check it out? Thanks in advance, this is very frustrating to me, not being very good at all with automotive electronics. Please help.