From your advertisement-
"The car appears to have the correct and original rear and bell housing. The rear has the factory 3.50 gear traction lock unit and is fully functional with a date code of 8D24. The bell is dated 8G20"
The car left the factory on June 11, 1968. The bellhousing was cast on July 20, 1968. What's the date code on the transmission tag? Does the VIN stamp on the transmission match the engine? The car is not that late in production (IMHO) to receive a 1969 transmission, some '68 Mustangs were built a month later.
1912 Model T Ford touring Salmon (ugh!)
1913 Model T Ford Touring original Black paint
1915 Model T Ford Roadster Black
1915 Model T Ford touring Black of course!
1967 Cougar GT 390 Cardinal Red / Black
1968 Cougar GTE 427 Augusta Green / Saddle
http://www.supermotors.net/vehicles/registry/15029/50071-2