these are the ones i bought

http://www.ebay.co.uk/itm/2-x-12V-DC...72.m2749.l2649

it says gearbox on them so i assume they are gear but until they arrive and i can tear it apart i dont know the quality

looking for a brushed controller im afraid

As for design im going with a basic flat chassis and bolting everything to it, once i got that sorted i will move onto something a bit more exciting.