Well, I'm making progress in my quest to get the fuel guage working on this '90 240 wagon...

Inside the fuel tank access panel under the floor, I see a round hatch on the top of the tank that holds two fuel lines and a 3-wire bundle, one of which is a ground. The wire bundle is sheared/rusted off flush right at the little hatch.

I believe the hatch itself is called a 'sending unit'. (Curiously, the car starts and runs fine...I would've thought the internal pump wouldn't be working if all the wires are disconnected??? but I digress...).

How do I get the hatch off? It looks like I should be able to tap it with a small chisel to loosen/unscrew it counterclockwise (after disconnecting the fuel lines, of course)? Is there a better way?

I'm thinking I can just swap it with another unit from the junk yard. Or is the wire bundle removeable/replaceable separately, somehow?

Any help/advice appreciated!