Removing crankshaft spacer from Craftsman/Tecumseh

Guys,

I need to open up the case on an old engine (Craftsman 143.216182/Tecumseh V60-70223G) from a Craftsman 917.285260 shredder/mulcher. Trouble is, there's some kind of collar/spacer affixed to the crank and I can't figure out how to get it off so I can slide the cover over the shaft. It's got flats which would seem to imply that it's threaded, but there are no visible threads. I've tried a breaker bar, but I can't get it to turn at all (it shouldn't be that tight, anyway). I haven't tried heat. Would this be pressed on? If so, how do you remove it other than splitting it (because I have no idea where to get a replacement)?

Parts diagrams for the engine don't even show the part, and the alleged replacement crank (Tecumseh 30856) doesn't look like this one -- which kinda makes me think the cross-reference may be wrong.

Any help would be greatly appreciated.

Thanks.
 
Would upload pics, but the server just sits and spins when I try...