Okay, where to begin.Let's just stick to production as there are plenty of 1-offs that used these drive units or made their own.
Production, there were a bunch of 6-wheel drive units most don't know about:
CMC had the 2-6-0 Mogul and the 4-6-0 10-wheeler
CMT had the 2-6-0 Mogul, 4-6-0 10-wheeler and the Camelback
Glenn Toy Trains had the 0-6-0 Switcher
Harmon had the 4-6-6-4 Challenger, 4-6-4 Hudson and the 4-6-2 Pacific
Kresse/Harmon had the 4-6-4 Dreyfuss Hudson
Lionel LLC had the 4-6-4 Hiawatha and the 4-6-4 Commodore Vanderbilt
Liberty Lines had the 4-6-4 600E and the 608E Switcher
McCoy had the 4-6-0 #6 Chief Cle Elum
MEW had the 7/16" scale 4-6-0 Colorado Midland
Randall Trains had the 4-6-4 Hudson (but they didn't sell it with running gear)
Thorley Hoople had the 4-6-0 #89 Dr. George Cody
Roberts Lines had 4-6-6-4 Challenger, 4-6-4 Hudson and the 4-6-2 Pacific (these were based off the Harmon patterns, but better detailed)
There were a few 8-wheel drive locomotives as well:
Kress/Harmon had the 4-8-4 GS-4 and the N&W 4-8-4 "J"
Lee Lines had the 4-8-4 GS4
Here are some pictures of some of these:
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(top to bottom)
John Daniel's Railway Lines GG-1
Lee Lines GS-4
Kresse/Harmon Dreyfuss Hudson
Richart Cascade Bi-Polar
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(top to bottom)
CMT Camelback
McCoy Chief Seattle
Thorley Hoople #89 Dr. George Cody
Liberty Lines #600E
McCoy #6 Chief Cle Elum
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Glenn Toy Trains 0-6-0 Switcher
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Randall Hudson (top)
MEW Colorado Midland 4-6-0 (bottom)
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Harmon Pacific
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Harmon Hudson
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Harmon Challenger
This wraps up the most common (if that could be said) of the 6 & 8-wheeled drive locos. I can answer questions about these, but I will not discuss production numbers at this time.
Hope this helps (I can't see how it couldn't),
ARNO