Incline parking and converter drainage

pishta said
Trans GO "No Yo-Yo" kit includes the spool valve that prevents convertor drainback.
"..A727/A904 NoYoYo W/ Manual Valve Shift Kit 1960-Up TF6, TF8, 904 and 727 3 Speed RWD 60-up Aluminum Case Transmission Includes New Manual valve, Mumbly Peg for easy rooster comb assembly and items for unit calibration. Addresses Converter slip-shudder. Leaks out vent or lever. Front bushing and seal burnup. Drainback Complaint .."

Yes it does and I won't say that valve does not work, but it is inferior
To the Sonnax design which uses a built in check valve that block flow completely in one direction and opens to flow as soon as the engine starts.