sending unit replacement

okay so tonight I'm going to drain out the gas in the tank and attempt to replace sending unit. The one in there looks like it has little tabs around the outside to possibly tap a screwdriver or brass tool to turn. However the new one doesn't have any place to tap tight. Has anyone come across this? Do you just turn till tight with your hand?

As always thanks again?
My experience has been, that you will need to re-use the original one. The new rings do not seat tight enough. Everyone I have installed has developed a leak.