I replaced a bulb in my dash a few months back. Just pulled the old one and took it to the nearest auto parts place (O’Reilly’s, I think). Found a replacement, paid a couple bucks for a pack of four and popped the new one in a few minutes later. I’m a mechanical moron, but not even I could mess that up.
If you are referring to the socket that holds the bulb and fits into the back of the gauge,most parts stores will have those as well. Carry one of the gauges with you to get the correct size socket .