if you're planning to DIY change it, i found this link. I haven't done it, seems like it may take a bit of time, maybe a day, but fairly straighforward.
DIY: Tranny removal and Input Shaft Bearing change - D-series.org
if you're planning to change it and leave it, and your clutch is fairly new, you could probably just change the input shaft bearing in the transmission and leave the clutch release bearing. But on the other hand, the clutch release bearing is so easily changed when you have the transmission out, so why not change it?
Also it would be a great idea to change all the oil seals.
Any standard transmission from 1992-2000 D series will fit. The one I used was from an EG Si/EX