proportion valve and strange cable question

[btorear]

I have a 71 3/4 ton 4x4 with a 396. Anyway, i can't find a proportioning valve for it anywhere. Everytime I find one that looks like it'll work it turns out to only be for a 1/2 ton. Any ideas where i could find something that'll work?
Also, there's a cable that looks like it should be hooked up to the throttle but it runs down to the transmission. It's been disconnected since I bought the truck (i am a novice, but learning new stuff all the time) what is this called? And it looks worn out...where can I find a new one. I heard that this cable has something to do with the truck goin intopassing gear when the accellerator is pressed down (which my truck doesnt do. That's another thing about this truck, it has a 396 big block but feels like it has no real power at all). Any help would be appreciated.
Thanks

[cdowns]

the kickdown cable for a th350 tranny should be available at gm dealership// the strange thing is i thought most all big block trucks came with th400 trannys??

[jimmydean]

I thought the prop valve for 3/4 and 1/2 were the same, only the hose connections were different?

1/2 ton front/front and back/back, 3/4 ton front/back and back/front (M/C to valve).

[Livrat]

The prop valves appear to be the same on both of my 1/2 ton and 3/4 ton boosters.. just the lines are different..

Yes the cable is for a T350 kickdown.. should be availible at the GM dealer

Big blocks never came with a T350 trans so you will have to take a small block bracket and modify it to work on the big block so you will be able to hook up the kick down cable

[cooters]

i n the mid 70's chev put a bracket on a back of the q jet instead of mounting on the intake which also has a throttle bracket in it

[qksilver]

67-72 4X4 never came with a big block...........

[btorear]

No, they didn't come with a 396 in 71, but that's what's in it. I don't really know what kind of trans. it has, but ill look and see.