Help With Proportioning/Combination Valve Identification

[cericd]

Thanks Keith, I don't know why I referred to my truck as a 1970 SWB C/10 with a 307. I mean, that's what it is but the braking system is now more akin to a 1971 SWB C/10 with a 307. I have added factory style front disc brakes and a restored Delco/Moraine from a 71 C/10. I currently have an aftermarket combination/prop valve and I would like to replace it with an appropriate Delco, Bendix or Kelsey Hayes valve.