I buy all my trailer parts at Johnson Supply but they are electric not hydraulic, I haven't used a hydraulic trailer brake set-up in decades, didn't know they were still available! https://johnsonssurplus.com/products/search?keyword=trailer%20brakes

The funny thing about science is that if you change one miniscule parameter you change the entire outcome to the way you want it.

JB Rhinehart, Realist

A-Body's RULE!