it seems to me that manual mustangs are a lot more plentiful than camaro's, although i have absolutely no idea why, especialy as the camaro is a far superior drivers car..
even if buying new, i'd choose an auto, simply because i find that (dodgy knee not considerd) i find manual to be a pain in the arse on the road, especialy in traffic..
having said that, again horses for courses - if i were buying a sports car, like a vette or ferrari, then i'd prefer a manual, on the softer 'GT' type cars like the mustang or camaro or even large mercedes or jaguar coupes (more fast cruisers than sports cars in stock form) then auto is for me the only choice, driver fatigue on long journeys is far lower in an auto..