Travis wrote:

Is there more than one type of Shimano 6sp or is it all
intercompatible? I've heard that this was a standard class of cheap
Shimano groupsets and therefore that chains, chainrings, clusters etc
from one Shimano 6sp bike ought to work on any other one.

Sheldon Brown has these things well documented at:
http://sheldonbrown.com/freewheels.html

He says that there are two standards for 6-speed sprocket
spacing, 5 mm and 5.5 mm. And two different chain widths to
match.

John