I have to assume that the o ring & white button thingie you're describing is an anti-syphon rig, which doesn't have to be messed with at all.
The suburban uses a big socket, the plug is metal and has a different coloured centre circle, which is the anode (meant to protect the tank from corrosion) Not sure of the size... my atwood takes a 7/8" and its certanly bigger than that.
83 sweet sweet days camped in 2008 - not easy in my neck of the woods!
- Salem 401-2b; 31" Sony Trinitron and two channels on the antenna.
- Smokin' hot wife... 2 boys, 25 and 10.