replacing a valve

i am replacing a valve on my truck because it is stuck in the open position. Since when i air up the rear drivers side bag and the valve stays open i only need to get one valve correct?

Before you go tearing down your entire setup, have you checked to see what's holding it open?
Disconnect the wiring to see if it's still stuck open- if it closes, then you have a wiring issue.
You may also just have some crud stuck in the valve that's holding it open- in that case, you can disassemble most valves without taking them off the truck so you can clean it...
Just trying to save you time and money- I hate taking valves out of a system!

But yes, if that valve is completely toast, and it's just the lift or dump valve, that would just be one valve to replace. Good luck!

-Phil at FBI