Installing proportioning valve

[cole]

I did the disk swap to my 68 1/2 ton step. I was told that it didn't need a proportioning valve. I believed it until I needed to stop real fast and the backs locked up and I slid sideways. I went home and ordered the stock valve for the 71/72. I fabricated a bracket and found out that the line sizes are different or the fittings are different. After many hours with the tubing bender, new lines and a flaring tool I thought I was ready to role. I can't seem to get the rears to bleed. Is there some magic that somone out there is aware of? I Could use the advise, my wife is getting tired of pumping the brakes.

Thanks,

Cole