It isn't much as dasreboot said. On my boat I doubt it's even more than 2.5 inches as you can see by the attached pix. I was able to undo it by simply pushing the shaft and its coupling against the packing gland. The toughest is reaching the bottom two bolts of the 8 that hold the tranny to the engine. The splined shaft of the tranny is not very long (see pix) so once all bolts are off then you can pull it back and slide it out. Loosen but keep the two top bolts secured until all others are undone. It will be easier to control movement of the tranny until ready to pull it out.