I thought that RSB was only installed on the -500's, if the aircraft was in cruise and the speed picked up, at a predetermined mach figure the speed brakes deployed to slow the aircraft down before it pitched up. It was a while ago.
Remember, but not to well, doing some checks on the Yaw Sas system as the aircraft was reported it felt like it was jumping around either left or right turns, and found that the rudder in 1 direction only was moving the opposite way to that required.
I have many hours on them, trying to keep them flying, but not since 1994.