now that i am almost ready to reinstall my newly rebuild th400 back on to my 61 364 lesabre, what is the best way to messure to in sure correct cut on driveshift. I think the th4oo is about 5" longer then the dynoflow:confused: and do i need to change the front yoke. and can i reuse the trannie mount, and just move it down, retap and mount.:confused: thanks for any help.

When you bring the shaft to the driveshaft shop ask them. Most have different ways they like to proceed with this. Go by their recommendations & advice.
You will have to use the mount for the 400 I believe. With out a doubt you will need the 400 yoke.

Tom T.