To determine which Gas Valve your heater needs, if your heater is an “A” series thru a “J” series, you need to order the Basitrol Gas Valve, Item #20035. (LB White® #502309)
If your heater is a “K” series or later you need to order the Honeywell Gas Valve, Item #20125 (LB White® #521615 LP) for a Propane Heater or Item #20126 (LB White® #521616 NG) for a Natural Gas Heater.
#20125 - LP (LB #521615)
#20126 - NG (LB #521616)
Finally got it installed today after changing the regulator. Works great. Took right off. Thanks. I have heat again.