I started in 2004. That year, the messaging was “It’s easy to build a drivetrain out of the kit of parts!”–if you had a welder and could manage to figure out this funky and questionably-documented helical gear setup and drill motors whose gearboxes liked to puke their guts. (True story, our driver that year had a gearbox and said “I think this’ll work!” all optimistically…and then the gearbox dumped a bunch of planet gears on the floor.)
In 2005, the original IFI Kitbot came out. John V-Neun and Paul Copioli were the driving forces behind this, JVN on the sheetmetal frame and Copioli on the first widely available gearbox that was actually meant to take two CIMs (which was itself a novelty, we had two CIMs total the year prior). The result wasn’t quite perfect (Copioli was working for Fanuc at the time, which was all metric, so the output shaft was metric which made it trickier to find other keyed sprockets for a then-very-US-heavy crowd), but it was such a tremendous upgrade over the year before it was hard to give him too much crap over it. (Legend has it that the gears inside the gearbox were the first big order for a little no-name garage startup in Indiana.)
2006 was a total carryover.
2007 saw the original gearboxes banned by rule (there was a different philosophy about the kit then), and replaced with the then-new BaneBots planetary gearboxes. They were ill-prepared for the abuse of a defense-heavy game, and many teams had catastrophic failures. (I’m pleased that they got it together since then.) On the plus side, 6" AndyMark FIRST Wheels made their debut.
2008 saw the drive gearbox switched again, to the original square-case AndyMark Toughbox. Cheaper to produce than the cast aluminum housing of the Copioli design, and a 1/2" output shaft. For FRC purposes, this was just about perfect.
2009 was the changeover from the IFI control system to the cRIO, and I don’t know if the changeover to the AndyMark C-Base was driven by that too or what. But that’s what we got, still with Toughboxes. And, of course, rover wheels.
2010 had these funky stilts added onto the C-Base to clear the bumps. They were…okay. Also, 8" FIRST Wheels in both the gray rubber and the white rover wheel material, so you had hope for turning in a 4WD.
2011-2012 were, as I remember carryovers from 2009, but with HiGrip wheels instead of the slick Rover wheels. Edit: Also, they used CIMple Boxes.
2013 saw the addition of belts in the drivetrain, replacing chain. Big improvement!
2014 was the AM14U, and you know the saga from there.