I believe you can still get that valve from Sealco, they are locate din Ax and most truck shops can get it for you, I can't remember if they will sell direct to the public or not, but will talk to us.
Also John there would have been a provision for a push to release button in th edash also, this operated from the emergency air tank to release your brakes at least once in the event you ran out of air in the main tanks, the newer valve in there most likely does this operation as well.
