R 20 P/U 2WD V8-454 7.4L (1987)
Vacuum Regulator Valve: Description and Operation
Manual Valve
Establishes range of transmission operation as selected by the vehicle operator through the manual selector lever.
1-2 Regulator Valve
Regulates modulator pressure to a proportional pressure, tending to keep the 1-2 shift valve in downshift position.