78 3/4 ton Master Cylinder and Proportioning valve question

[Yukon Jack]

I have removed a manual brake master from my 1970 K5 and have installed a master cylinder, booster and proportioning valve from a 1978 3/4 ton.

I removed the donor parts quite some time ago and I don't recall which reservoir is supposed to feed the front as opposed to the rear.

I currently have it hooked up with the front reservoir going to the proportioning valve to feed the front brake lines.

Can someone with a 78'ish 3/4 ton take a look and see which reservoir feeds your front brakes? I believe your proportioning valve should be on a crossmember about below the engine fan.

Here is how mine is presently ran

Thanks

 

[ntsqd]

Normally the rear res feeds the front brakes. This isn't always true, but it is at least 90% true.

 

[goldwing2000]

If one reservoir is larger, that one will feed the front. If they're both the same size, it doesn't much matter. The piston is the same size all the way through, disc brakes just require a larger volume of fluid over time due to the way a caliper "self-adjusts".

 

[Yukon Jack]

Thank you!