Proportioning valve swap?

[jk3078]

Well we nearly got A.R's truck back together this weekend, just hung up on the proportiong valve and a few other odds and ends. The truck is a 70' chevy C10 with manual drum brakes (before)and the axle we just swaped in is a 3/4 ton 44 from a 76' with discs. I have heard to make this work you need to swap out the prop. valve but the one of the 76' wont work. Different brake line size's, 2 front lines instead of one, I dont see a way to make this work. Is there a different application that will work? If so do you have a Napa part #? What would happen if you didnt swap this part at all? I'm stumped so any help would be great, thanks.

O,and hears the specs on A.R.'s truck.
70' C10 custom fleet side long box
costom bumpers
350 with rebuilt q-jet,
headman headers, 3' of 2.5'' dual strait pipe,
465/205, new clutch
shaved 8 lug 44 with 5-760 x's, drive flanges,
shaved 1 ton 14bff, welded
4.10 gears
4'' rough country, 1'' zero rates
37x13x16 boggers on white spokes

 

[Muddytazz]

You need a prop valve off a 1st gen that came from the factory with front disks....I know the 72 did, maybe the 71 and 70 did also, but you'll have to look.

I converted a 68 to front disks awhile ago and he got a prop valve off a 72

 

[jk3078]

Ok, that makes sense. What about power brakes? Would they also have to be from the same year span of donor truck?

 

[Muddytazz]

I'm not 100% positive on that one. He used the booster off a 72 but the m/c off a corvette. You might want to look thru the 1st gen forum cause I know there was a post about this a while back, maybe a yr ago IIRC.