Just so you know on a 6speed it is anything but an easy swap. The 5-speeds had a separate belhousing that would just bolt onto the tranny.
The thing with the 6-speed is that the belhousing its self is part of the transmission. The belhousing is aluminum and the case is cast like that of a 5-speed but what happens with the 6-speed is that all the internals are held between the belhousing and the back of the tail stock. I know that when working on these transmissions internals you have to remove the tailstock and work you way to the front piece by piece. I am not sure if there are even extranal bolts on the holding it to the cast iron but know that you can't just pull it off and replace it...you have to take the whole tranny apart.
Now I am not a trany expert by any means and I could be 100 percent wrong but I watched mine being put together and this is how it was done. Infact when they put it in the parts washer they had all 3 pieces of the case apart and the last part they detatched from the main case was the belhousing.
Good luck and let us know how you make out.
RyanB