Proportioning valve ???

[findog78]

I have a '69 C10 that I converted to disc from a donor '71 about 10 years ago never had any issues with brakes or backs locking up. I recently got a new master for a '71 disc which is way smaller and has different size reservoirs. After reading several threads in here sounds like I should have had a prop valve. I snatched one off a 90's truck from junkyard but after I got it home looks like the lines from prop valve to master are backwards. Instead of front line to front of master and back line to back its opposite? Other pics of prop valves in the threads and online aren't backwards? Also the line diameter itself is smaller to the back reservoir? After more research it looks like my old master is a 3/4T? If I would have realized the 3/4T master was bigger and had bigger bore before I painted the smaller 1/2T master I would have exchanged but this is what I have now. Will the prop valve I have work or can someone shed some knowledge my way? The bottom fitting of the prop valve to brake line is smaller too. I'm tempted to scrap the prop valve totally and put it back the way it was?

My old set up... new master w/ 90's truck prop valve...and CCP prop valve