Dear SF: Do you know where the On/Off shift solenoid is on a 1994 GMC Safari.
Welcome and thanks for your question. If you are referring to shift on/of solenoid, they
(shift a, shift b) are at the back of the valve body.
Can be removed after taking down the transmission pan. A spring loaded clip needs to be
removed, then the solenoid can be pulled out. A spring loaded valve is behind
the solenoid, inside the valve body bore.
GMC Transmission Shift Solenoid Location