I WAS ACTUALLY WONDERING IF THERE IS A UPGRADE FOR THE ENGINE MOUNTED COMPRESSOR, I MOUNTED AN ON-BOARD AUX COMPRESSOR FOR 110 POWER.
well I installed a shut off at primary tank, crimped off hoses until the gauge stopped dropping from the remaining pressure in the lines, looks like final repair will be the foot valve, ordered overnight from Memphis equipment, will see.
appears truck had a ton of air system issues after all, likely stemmed from lack of air tank/water draining (rust in system). high condensation from overrunning the compressors due to leaks.