Automatic to 4 speed Conversion in '65 Formula S

The 4 speeds had a 10 in clutch stock from the factory as did taxis and some fleet vehicles.Even my 6 cyl 65 Barracuda 4 speed had a 10 in clutch.It bolts up to the same flywheel that the 9 1/4 does . I have taken out the small ones and put in the 10 on all my 65 and 66 standards even the 3 speeds . As for what trans to use I think I'd go with a 66 unit with the 2.66 1st gear and 1 to 1 4th. That overdrive unit with the 309 1st gear really runs out quick .It's good in a 6 but with something that makes power it works against you.