A new can of worms, and how in the world did I ever do that?

Ok, so let me ask you this if you had replacement parts for water heaters do you think most would be universal in reagrds to a commercial water heater and a residential water heater?

See I have the following:

Flue tubes (I know it is for gas powered)
Bottom head and top head discs (not sure what these are)
burner supply tubes
heat traps
baffles
MAIN CONTROL PC boards

There isn't a water heater chat sight out there is there?