Q - I was considering a T5 swap into my 64 121 and was wondering what parts I would need?
A -For a 64 121 I would suggest that you use a T9 instead of the T5.
The T5 is going to be too wide at the top for the trans tunnel. Although the trans tunnel can be modified to fit, it will be easier to install the T9.
For either installation you would need an adapter plate, slider yoke, and clutch disc with the correct splines. For the T5 you would also need a modified clutch fork and Ford release bearing. Listed below are the parts and prices for the typical T5 swap.
B20 T5 adapter prices:
Adapter plate -1 inch - $175
Modification to cable or hydrualic clutch fork - $40
Clutch fork core charge if not supplied - $50
Ford release bearing - $50
Special pilot bearing for V8 T5 - $25
Heavy duty clutch disc with Ford 1 1/16 x 1" splines - $140
Q - I was wondering if the parts from a T5 are similar to the T9 internally.
A - There is no commonality between the two transmissions that I know of. Basically the T5 was made for Ford in the US by Borg Warner and is now made by Tremec. The T9 was made for Ford in Europe. It is the most commonly used transmission in kit cars and for upgrades from 4 to 5 speed in older sports cars.