I'm just putting this out there, (just a feeler to see what response I get), but what IF #206 didn't have a blown engine? Not to say anything I might be un-informed about, but in looking at various photo's of #206, (pic's I saw on rrpicturearchives.net ), her stack is capped.
Now I know they don't cap stacks for a blown engine. Now I read as well, she was used as trade-in credit towards the purchase of 4 new loco's for the suzy-Q. (trade in back in 1988) I am venturing a guess that you might not be inclined to trade in a totally dead engine, as an engine with a blown prime mover wouldn't have as much value as one that maybe still ran.
All 5 of the other alco s-2's owned by suzy-Q were scrapped, (why weren't they traded-in?), and yet the last one left, with a blown engine no less, somehow had trade-in value? I am piecing together small clues and think maybe #206 is not as gone as we think, and she may she be very much able to get running again, with out a major fix-up job. After all IF prime mover didn't have a massive failure, then perhaps she was retired for other reasons. I'm not saying something didn't happen to her, something did. I'm just speculating she didn't have a "blown engine" Any thoughts by you guys out here?