Pacbrake PRXB for 10 years. The OE check valve at the compressor had to be replaced to avoid air loss when parked. The small compressor finally gave out so I bought a 100% duty cycle Viar 480 and put in a 3 or 5 gallon long tank. Kicks a$$. Added a 22 inch Grover air horn for errant driver wake up calls!!! I have a toggle switch so I can use the steering wheel horn button for stock horn or air horn.
With my G-56 the PRXB is phenomenal. A few years ago I was coming WEST over Donner Pass on interstate 80. 4 adults in the cab and a dog, towing a 24 ft T Trailer fully loaded, going down the pass, I never touched the foot brake. 6th or 5th down the hill with the pacbrake PRXB.
104,000 miles and still have the original front brake pads.