Went from a powerglide to a turbo 400, now leaking problem
 

I went from a powerglide to a turbo 400 on my 66 impala. When I had my drive shaft alterred to fit the new tranny output the technician told me I had to plug the inside end of the tranny output with a bolt and sealant. So I did so and put it all together and now It leaks about a liter a week. My question is did I get it wrong and plugged the tranny when I was supposed to plug the drive shaft adapter? I am wondering because I cant see that there is anything keeping the fluid in the tranny other than the gears interlocking with eachother which isnt going to be water tight. The pictures I attached are of the drive shaft adapter that I am wondering If I need the plug the end.

Didn't they make a closed yoke?

I used the yoke that came with the turbo when I bought it, it wasn't sealed then so I assumed that it did not have to be. But now that I think about it seems that it must need to be the way that I am using it.

best thing you could do for cheap is to go to a junkyard and find a used driveshaft. check the diameter and number of splines inside thenhave the length adjusted for your car. make sure to clean the outside of the tranny mating end. that is the only sealing point that should be with your tranny.(rear tranny seal)