Adjustable Proportioning Valve Help

[jason999]

Hello,

My 66 C10 has a front end, and rear axel from a 1981 Long bed Chevrolet. The brake system came from the donor truck, but the booster was replaced and I'm not sure it was the same as stock. It has the original combination valve.

So, I have disc front brakes and drum rear.

I rebuilt the rear brakes and replaced the drums.

The problem is that my back brakes lock up before the front, when I brake hard. I am thinking that my old truck is lighter in the rear than the donor truck.

I have decided to add an adjustable proportioning valve to lower the line pressure to the rear.

Can anyone recommend a specific proportioning valve for my application? Any help would be appreciated.

Thanks,
Jason