Can someone explain what this is ? My trans guy was talking about adding this to my trans while they were doing some other things. The way he explained it, sounds like some kind of “overdrive” switch for a TH350. With my current trans and gearing, I normally run around 2400 RPM at 65mph. He said this should drop some with the lockup and allow me to run 70 MPH at about the same RPM range.