There is no model # stamped into the valve I recieved from heatervalves.net. Only Ranco HF
Im not sure How Denny got his apart
Denny Pic. Heres a pic of My original Ranco
Pic You can see in that pic the Bellows tube is cut.
I found out later that made the valve useless and not a good core for turn in/ rebuild.
That is why I had to find a source for a valve.
Hopefully Denny will post up about that disc, I dont believe there is a need to remove it.
Good Luck on your rebuild
Those tabs are a headache. You can see in that pic of my original valve, one of the tabs is ready to snap off.