Do you need to pull the motor out of your 1970 Olds 442 change rear main seal?

No, you do not need to remove the engine (pull the motor) from your 1970 Oldsmobile 442 to replace the rear main seal. While it's a challenging job, it's generally considered doable with the engine in the car. However, it's a significantly more difficult job than doing it with the engine out. You'll need to work from underneath the car and have the necessary tools and patience.