Thanks Earl! I'll have to see if I can see this on OY/OM if I make it to Chama again. What I've seen in diagrams of the A1 system as used on some engines was a double check valve that went in line so that a plain triple valve could be used to apply the brakes on the engine with the automatic brake, but still be able to set and release or bail off the engine brake with straight air via the independent brake valve. I wonder if the adapter plate was a means of achieving this while using a K1 triple with attatched resvoir?