drivetrain swap
 

Hey Guys,

I finally found a donor car for a total drivetrain swap. Going to put a '70 455/TH400 from a Bonneville into a '72 LeMans that currently has a 400/TH350. My ? is what do I need to modify, change, move, or replace, besides the motor mounts and tranny support bracket? What should I do about the driveshaft? Will be upgrading the rear end also. Any help or advice is welcome. Thanks

You will need to get the drive shaft shortend as that model long tail shaft tb400 from the Bonnie never cam in the A body cars and you will also need to get the bigger tb400 yoke and U joint for the transmiassion end of the driveshaft also.
Also the tb400 makes its down shifts with a electric switch above the gas pedal unlike the downshift cable you now have. You do not need the switch if you do not mind making the down shifts by hand.
I would use the drive shaft out of the bonnie as it has the needed size yoke and if it is not too badly rusted on the inside when they cut it open to shorten it as the tb400 shaft is bigger/stronger than what you have now in the tb350 shaft
Your should try to grab the steel trans lines from the bonnie also as shortening them by taking out a section and rejoining with trans line hose in a straight section of line is easyer then trying to re bend your tb350 lines to mate up to the tb400.