I carry some universal blower motors, C.F. motors, ignitors, xformers, a couple of universal ignition modules, th. couples, some relays, t-stats, various capacitors, and a fan center thats been on my truck for 5 years.
Thats basically what I carry in my truck aside from wire, various fittings, and tools.
I carry no gas valves, circuit boards, pumps, inducer motor assemblies etc. If I did, I would need an 18 wheeler.
Very rarely does a gas valve go bad...not including smart valves, or a pressure switch, or a flame sensor.