After going over the installation of the Jakes on my engine last Friday I learned a couple of things. (ain't life wonderful?)
He added a solenoid inside the governor ($345.00) in place of the High Idle Solenoid which will give me both the High Idle back and does the switching 'on' of the brakes. It's all or nothing.
There's either a Master or a slave on each cylinder (the slaves are connected, each to a master) and the new solenoid allows only operation of all 8 simultaneously. Remember though, that these are 4 valve heads the jakes only close TWO of the 4 valves. Another reason that Jakes on a Detroit aren't as noisy as on, say a Cummins.
After getting my 'hands on' classroom lesson of the day I came away from that meeting with two things in mind. First, the quality of the product from Jacobs, and secondly the joys of knowing and having a top mechanic like Dave who not only knows what he's doing but is willling to take the time to explain the where, when and why of what he's doing.
My unqualified thanks to "Uncle Ned" for sending me and my Bus to Dave!