Propshafts - Advice needed.

[Enoch]

Hi clever peeps. Just been scratching my head regarding the propshaft. The one that came off the sierra is in two pieces. It would seem that it could be fitted while the box and diff are in situ as it has a splined joint which would allow the two ends to be manipulated in to place by sliding the two prop halves up together. Am I correct in assuming that a single piece shaft would be used in the roadster and that the engine and box would need to be moved forward to get the thing in place? My box is an MT75, it has the big rubber donut fitted.
If I need to move the engine / box, I would prefer to do it now before the exhaust and all the other bits are fitted.
Thanks in advance,
Enoch