I have a 320 cat hoe that the auxillary foot pedal is plumbed to the travel how do I plumb it to run a hydraulic thumb
Not sure you can, not easily anyway. The pedal is known as the "straight travel pedal", it's an accessory not fitted on all machines. The "work tool pedal" is on the LH side of the floor, the straight travel pedal is on the right. In effect you'd have to re-plumb the pilot system to the pedal, then add a section into the main control valve for a thumb (because I'd bet money there isn't a spare section in the valve right now), then add all the main lines up the boom & stick to the thumb cylinder.