I don't have CAD pictures, but you don't particularly need them for the 6WD designs I've had a hand in.
The first stab at 6WD was in 2006, with
Chomp. We used the 8" Skyway wheels in the kit along with a pair of 8" IFI wheels, all driven with two small CIMs in the Kitbot transmission of that era (an option still available is the AM Gearbox from AndyMark). The combination allowed for nice turning and was plenty solid, although ramp climbing was an issue. (The issue never really was diagnosed.)
The lessons learned from Chomp (along with some funds to facilitate it) led to
Uppercut. This year, we used the AM FIRST Wheels from the kit of parts, cut the rubber tread molded on (burning myself in the process), and riveted on incline conveyor belt from McMaster-Carr. We used one large and one small CIM driven by Gen2 AndyMark Shifters. We used the pneumatic shifters for the added shift speed compared to servos, and because we'd been learning pneumatics in the off-season; the large CIM was used because one of the small CIMs was needed elsewhere. We also used
JVN's drivetrain calculator to figure out the sprockets needed to give us the speeds we desired. (In theory, about 12 and 5 feet per second.)
The result was the best drive system all-around from four years of trying, though it wasn't without its flaws. Of note:
1) The kitbot loved to lose nuts and bolts. I'm hoping we'll have the ability to rivet by Kickoff.
2) In the absence of all the nuts and bolts, enough abuse on the front bumper will cause it to bend mercilessly. (As our arm never worked through Palmetto and Brunswick Eruption, we played a lot of defense.)
3) We should've mounted the AM Shifters on the side with more weight (the side with the tower). We broke the screws in the left center wheel on Friday at Palmetto, meaning we couldn't power the left center or rear wheel. Only the front wheel would get power from the gearbox, and it was off the ground for all the weight in the back. Were we to adapt this design for 2008, I'd move the gearboxes to the heavier side. (Granted, this makes the weight distribution a little worse; you can move other things forward if need be, though.)
4) We used the frame stiffeners in the kit to mount our gearboxes on Uppercut, not realizing that they blocked the chain path. We fixed it with idlers on Uppercut, but I'd rather find another way in the future to eliminate some weight and complexity. (Flipping the gearboxes upside-down from how we mounted them
may fix the problem; I don't have a means of checking.)
That's the business-major version of the various 6WD setups of the greater Columbia area. There are others who will have plenty more to offer. Good luck!