Jack Steward, It is my opinion that the handle you have pictured is a modified Stanzel Monoline. When it became mandatory that the handle had to be in the "yoke tower" for the speed run, the original Stanzel handles had to be modified. As a side note the tower came into use, to stop whipping models during the speed run. Today it's standard practice to whip the model up to speed before the handle is placed in the pylon. Years ago there was a video (actually it was movie film) of a flyer who got so far ahead of his model while whipping, that the wire was wrapped around his shoulder! Since it was a monoline unit he probably still had control, but he was also shortening the lines, which would gave a false speed reading that was higher then the actual speed. Remember speed runs are done by a stopwatch, based on a specific line length. Stanzel had a standard challenge that they would give $1000.00 to anyone who won (or maybe placed?) at the Nats with a monoline unit in Stunt. The problem is that there is a lag in control response, so square corners are a big challenge. I never flew a monoline, but I've seen a lot in use over the last 60 years.
.