Junk yard radiator.....

The 66-79 F150 is a 26" core radiator with side brackets. However, it is 2.5" taller than a 26" mopar radiator. That could be a 'hood' stopper. Also you'll need to check your inlet/outlet configuration. Ford is RH top in and LH bottom out. If you had a 26" radiator in the car originally and you overcame the 2.5" height difference and the in/out positions, you'd have to drill new holes in the radiator brackets or the core support for mounting. You also would not be able to mount an original shroud.

Do you see where this is going? :)