First make sure it isn't a 5 bolt bell housing ..unless your motor is a 5 bolt bell housing . The swap is very easy.You will need the correct Flex plate ...AND MAKE SURE TO USE THE SHORTER FLEX PLATE BOLTS TO THE CRANK ,THE FOUR SPEED ARE TO LONG. Tranny mount is the same .You will need a floor shifter for a 65 -66 ,you will need a transmission cooler, unless your radiator is set up for it already .You will need tranny oil lines to hook up the radiator or external oil cooler .And you will need the starter for an automatic ,the 4 Speed has a shorter nose cone .You will need a passing gear cable to hook the passing gear ...and you will need a throttle pedal assembly for an automatic because the manual pedal assembly is not set up for the passing gear cable .
I read that the carb is different for a manual vs an auto. Can I convert my 65 carb to work with the 68 c4 setup? Does the kick down connect to the carb or just to the hook on the gas pedal linkage?
The carb will be the same for a 65-66 ,the passing lever is a cable from the pedal to the leaver on the transmission ..you will not need a vacuum can ,that was 67 up and for the air conditioning .The vacuum will come from the back of the intake and down to the modulator valve on the transmission .
You will need this tube for the vacuum line at the back of the intake ,there is also a brass fitting in the intake this tube screws into .a rubber line attaches this line to another metal line that goes down to the modulator valve and another rubber hose attaches the metal line to the modulator .This can be bought all new .