Yeah, by thinner I mean the aluminium seems thinner everywhere. Flick the core with a fingernail and it rings rather than thuds, the tangs to which you fit the fan are visibly thinner and the fins aren't as dense. As I said, mine's been on for ages and no problems, but it feels an 80 quid part, not a 400 odd Yamaha part.
But hey, it works well, no overheating, hasn't fallen apart. I'm happy!
As for the fastenings, it's the little clamps for the fan mounting I was talking about. They'll be a twat to get off if they were anything like mine, but they're standard fixings so loads on eBay and the like.
And no probs about the searches! This site is amazingly full of interesting facts and fixes and you'll be missing out if you don't search for stuff.