Here is my old lock ring. I think.
And what I was left with after that was all gone. Only 3 tabs that were recognizable and none of them were solid. They were all flaky too. They're still there and usable enough that I could use them to help position the new lock ring.
New unit on the left. Got a good price on it. New pump, housing, internal filter, and the improved design fuel level sender.
Updated wiring harness that had to be spliced in - easy. They even gave diagrams because some wires were different colors.
And here is the fix I came up with based on a suggestion earlier in this thread. Stainless self-tapping screws and washers.
So normally I would have just gotten a new level sender and separate fuel pump to fix those problems, but the other problem I was having was the non-existant lock ring. It was no longer holding anything down so I got fuel leakage pretty bad when the tank was full. If I filled up the tank too much, gas poured out everywhere. So I just got an entire new sending unit to get the pump, level sender, and gasket for the tank opening.
Got it all together the first time and fuel was still leaking everywhere from the tank opening under the sending unit. I was not pleased. I took it apart and realized the inner sealing surface for the gasket on the tank was warped slightly here and there, which I have not heard of before.
I didn't have much of a choice what to do, so I used a sealant. Permatex 85420 - fuel resistant. Not affected by fuel unless it's submerged for long periods of time, which this ring area never will be. Put a good bead under the gasket ring, and on top for between it and the sending unit, used it to seal the screws for the lock ring, and let it sit overnight. Fired the car up today and drove it around some hills and turns and it's still bone dry. I'm hoping it holds up!
I hope this information and pictures helps anyone else with no more lock ring tabs on the tank...