Small Engines (Lawn Mowers, etc.): Snapper clutch, clutch design, clutch components

Question
Hi,
I have a Snapper  SR140 3312513BE.  The clutch is going & I need to replace.  What part #'s and parts do I need & also what the smooth clutch kit?  I imagine mine doesnt have it because it jumps in gear.  
Thanks

Answer
Manual link:

http://www.snapper.com/manuals/index.cfm?rd=1

5-3103 Driven Disc is the most common part.

The smooth clutch contains parts 2-6 in the parts list.  This kit is only intended to convert old
Riders (up to Series 6) which were built with standard clutch components to the smooth clutch design. This will provide smoother starts, especially when the machine is incorrectly started from higher speed settings.  Your mower is a Series 13.

More info here:
http://www.mytractorforum.com/showthread.php?t=87980

http://www.youtube.com/watch?v=wXz6cu6gJkA

Eric