Nearly finished a 65 galaxie has a 390 with a 3 speed cruiseamatic. Problem I face is I want to fit a b+m megashifter into it. however the transmission is not listed in the installation instructions. Has any one done this or know if the trannys listed c4 , c6 , aod are similiar to the cruiseamatic. Or is it just a mod. to the length of the selector arm on the tranny, or should i just take it to a shop and let them sort it out.