i have been there with my 62! only year that uses the motor at a right angle to the hole in firewall. mine had a stripped gear. take off the tin cover and inspect the gears. if its the motor you can find one. if its the gear start asking around. I was lucky enough to have a member on here send me a good one! I have seem someone selling just the gear on ebay, but he wanted $80. I waited! If its the motor send me an email and i'll see if i have an extra motor. (did you check for voltage first? do you hear the motor running?)

1963 GMC Suburban