1965 727 tail shaft housing - '65 ONLY?

is the slip joint tail shaft housing for a '65 727 one year only?

Yes

So is the output shaft. However small block 65 parts from 65 318 poly motor 727 can be used to upgrade BB earlier ball and trunion style 727.
Doug

Done many times by many people

That's good to know

Can someone please explain a little more. I have many 65 and earlier cars and trans but have never bothered to save many of the 65 SB trans. Is it just the input and output shafts or something more?

Save the whole output shaft and extension housing assemblies off those small block 1965 727's. Keep the park mechanism intact and I would save all the cables unless they are toast.
Console shift valve bodies differ from push button so I would save those as well.
Most guys get rid of the early input shaft and reaction shaft and replace them with 1967 and later stuff as the spline count changed between early and late.

Actually if you have the room - just keep the whole trans - everything can be transferred to a big block case.

You never know when you may need something.

Remember - there is no such thing as a poor junkman.

Thanks for the education Transman, I learned something new today. Now I won't have to spend so much time hunting for 65 BB trans I can use some of the 62-64 ones I have around.

That's good to know. Still can't seem to give these things away though.

I usually upgrade the reaction support (or complete pump) and the input shaft to 67 or newer. This allows current spline converters. If you use 71 and up reaction support and front drum you also get the benefit of the wide bushing drum.
Doug