The switch pitch 400 was used in Buick, Olds, and Cadillac from 64-67. You can identify it by shorter splines on the stator support shaft, or by the solenoid on the back of the pump. Remove the pan, if the second wire goes to a pressure switch on the valve body, it’s not a switch pitch. The switch pitch was discontinued because of added cost, as some people complained about the whirring sound the converter made on the high stall position. The converter also isn’t the most durable design, from what I have heard about 550-600hp is really pushing your luck.
Most people adding a switch pitch wire the high stall on a push button, and also on the brake light circuit. When your on the brakes at a stoplight, the converter is on the high stall setting, and the engine will idle better if you have a manly camshaft.
You can convert a switch pitch to a standard 400 by changing the forward clutch, pump, and ideally the valve body. There were some hydraulic changes made to compliment the switch pitch converter. There is a good article on the V8buick site, the article is by Mark DeConti).
