A few years ago I had five pairs of them, due to a trade. Not one did not have a cracked axle. It takes only one split axle to ruin the truck. I took apart one truck and found that three of the four axles had split, and the fourth had a suspicious gray line that I interpreted as "split impending." I gave away two of them, even paid the postage, one to Germany. Never heard a word of thanks--the trucks must have been as bad as I thought they were!
They do have nearly correct wheel diameter and spacing for a Baldwin Centipede, and NWSL did sell replacement gears at one time.
Shoot me an email (peterknolan@gmail.com) rather than a PM (I'm just not looking at the forums so much any longer) if you still want a pair. Or a mechanism. Or the whole shebang. All I want to do is recover some modest costs and shipping and handling. Recognize that I still would have to find the shebangs in all the unpacked boxes.