This model does not have a retaining ring. when you look thru the access hole you see the fuel pump/sending unit assembly. It's about 4" diameter and kind of the size of a coffee can only it's made out of plastic. I can wiggle it a little, but I can't pull it loose. I looked at the bottom of the tank directly below the assembly and I can see some "spot weld" marks which leads me to think that the assembly is kind of plugged into a metal bracket to hole everything in place. If I pull real hard it might come up, but if not I'd break it and were are talking close to $300.