Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Some places will change the solenoids when they do a rebuild and some do not. It could also be that the solenoid was changed, but the connector is broken (they get brittle with age and heat.
The solenoid is #5 in the picture:
With the transmission pan removed, unplug the solenoid, then remove the solenoid retainer (spring clip, #395) then pull the solenoid out (#396 in the picture below)