If someone on this site doesn't have a good used one, you should be able to source one from a parts house such as NAPA. This motor was pretty commonly used across the Ford product line. LTD/Galaxie, Torino/Fairlane, 67-76 T-Bird, Granada, and a few others used this motor. So availability shouldn't be a problem. If you didn't want to go that route you could always contact one of our on site member/venders such as Don (Ohio Mustang Supply) or CJ Pony Parts.
EDIT: 1971Mach1MCODE, please disregard the info in my post. Must of had a brain f**t and missed the "Pancake" part of your post. All the info I gave was for the door motor. Your best bet would to do as Carolina_Mountain_Mustang suggested and look at West Coast Cougars site. The 69/ Cougar used the same motor and had a Cougar part number.