Best I found was a Cable/Clutch control Bulldozer in Scale at the Amhearst show a couple years back.
These are hard to find, Hydraulic ones are everywhere.
Last year I found the K-Line 3 car Heavyweight Red Cross rolling Laboratory set still in the box. Never knew they existed till I saw them, Had to grab 'em.
Shows are good for that, better than any other forum for finding what you didn't know existed.