1980s /6 bolt up to 66 904?

f your 66 still has the original transmission, it will have a small snout torque converter. The crank in the 80s will have a larger recess in the crank for a 68 and up torque converter. There is an adapter available that will enable you to mate the small snout to the large recess. You will also need to use the 66 oil pan and oil pump pickup. Then everything will bolt up.