After looking thru the service manual, there is a shift rod. So you could have some problems going on.

Personally I would chock the wheels, put on the parking brake, have someone hold the brake and torque the motor slightly in drive while you are looking under the car to see what is going on. It might give you some insight to what is happening.

Possibly the rod is adjusted close enough to work but on the edge of not far enough. Maybe a slight adjustment is needed.