Go to david keys toploader site
I think 64 and early 65's had a different bell pattern and different spline on the main shaft -
His site has pictures and if the one you are looking at has a tag you can ID it
Also there is wide and close ratio's.
Pulled this off his site
The Toploader was used in production from 1964 to 1973 in almost every model Ford car and a few foreign cars.
A 1-1/16" input shaft was used in motors from the 200 c.i. to the 390 c.i. while the 427, 428 and 429 were available only with close ratio gears. The 1-1/16" input transmissions are available in both close and wide gear ratios.
The gear box was built in 3 case lengths. The 1964-65 Fairlane, T.V.R., Griffith, and Sunbeam Tiger case is 25-1/2" long. The AC Cobra with 427 and 428, all Mustangs, Falcons, Mavericks, Cougars, 1966-67 Fairlanes and Comets use 24 " transmissions, while all full size cars and the 428, 429 Cyclone and Torino use the 27" box. The 1964 Toploader used a small 4 hole maincase with the small O.D. bearing retainer. All 1965-73 cases were wide 8 hole cases with the large O.D. bearing retainer.
In 1964 and early 1965 a few transmissions used a 25 spline output shaft which proved to be defective. These were quickly dropped from production. Normally all motors 200 c.i. to 390 c.i. use the 28 spline output shaft. All 427, 428 and 429 motors use the 31 spline output shaft. There are a few exceptions to the above information. The toploader was produced in 133 different models.
