MG Car Repair: retainer for fuel tamnk float device on gas tank, retainer ring, rubber gasket

Question
I am n the process of rebuilding my fathers 78 MGB. I have cleaned out the tank and ordered a new sending unit as the old one was gone. I am wondering about the retainer ring that hold the unit to the tank. I notice three prongs on the tank and three prongs on the ring. Also I notice 3 small places on the ring itself. How do I install this ring. Thanks

Answer
Hi Henry,
First put the thick rubber gasket into the recess and then the sending unit which is keyed so as to only go in upright. Then slip the retainer ring in with the ears out and you will see that if you use a punch or a flat blade screwdriver on the ears you can bump the punch or screwdriver lightly with a hammer so as to rotate the ring so it will wedge in on the ramps and tighten inward to hold pressure against the sending unit plate. There is no locking device to hold the ring after you have rotated it tight. It is not necessary as in all the years I have been working on MGs, I never seen one come loose. There may be a tool to rotate that ring but I have worked in several MG dealerships and never seen one so I always used a screwdriver and a light hammer. Use no lube on it.
Howard