I agree 100 % with using late model components because manufactures put a lot into research. I would get a complete system from a late model bobtail with hydraulic brakes to make sure everything is meant for each other. As far as the old limiting valves. That was from stories before my time and I bought my first semi in 1964. All the trucks I had with front wheel brakes disabled were dangerous. We took the brakes off for weight savings, but it made them more dangerous on slick road. The drivers locking up is what causes a jack knife. I'll take the trucks we have now for safety that limit all of the tractor brakes when there is no trailer and have anti-lock.
