Yes there are two different boxes, no they don't both fit. One will be a K50 (what you're after) and the other is a T50. Take a photo and we'll identify it. Easier than trying to describe the differences.
Yes
Give me a few minutes and I'll put my experience with this conversion in the FAQ.
Edit:
http://www.rollaclub.com/faq/index.php?tit...s/K50_into_KE20
My article from 2003 converted to FAQ format.