Got the drill motors for the drive yesterday and set about hacking them into usable drive motors, I'll include the link for anybody who wants it because they were a great little find. They're bosch psr 18v drills which are usually around £60 brand new and i got them for £12.50 each, granted there's no battery included but if you're only after the motor and gearbox it's no problem. A couple of things i've discovered about them, firstly they don't have all metal gears which although annoying isn't too much of a problem, they are really compact..like stupidly compact and the output shaft is tiny which means it's very unlikely to bend. The motors are 600 sized Johnsons rather than your standard cheapo chinese 550 which considering the price is even better, also the build quality seems pretty solid, better than standard drills anyway. Some bad points though, the GB and motor are not attached yet the holes to mount the motors are there, it's like they forgot to put the screws in.....weird right? Also the chucks are on TIGHT, after some advice and a fair bit of head scratching i figured out a pretty fool proof way of removing them, you take the gearbox apart and get a round piece of steel in some pliers and wedge that in between the pins on the carrier plate, then you put a fairly big allen key in the chuck and twist the two in opposite directions, takes a fair bit of force but it does get the chucks off. Wow i just wrote a whole essay on my drive motors, anyway for any that are interested here's the link http://www.ebay.co.uk/itm/331196477100

And some pictures