removing fan motor from heater box?

Not sure how different a 70 is from a 72 but on the 70, the motor and squirrel cage assembly is slid onto the studs that go through the firewall. To slide it off the studs you have to remove the little round spring washers and then the spacer bushings. After that the motor and squirrel cage will slide right off. The motor mounting plate which the studs are attached to has to be removed by drilling out the rivets.

View attachment motor.jpg