Do you have the "Dragon Knight Saga" version of the game? If so, then things have changed, they've move about. They're not all in the flying fortresses anymore. The changes have gotten rid of almost all of the indistinguishable brown chests in flying fortresses, pretty much every chest is big, golden and surrounded by blue coloured lighting.
Belt -
Do the "seeds for the dragon statues" quest and mind-read the goblin Charlie. The belt is in his stash in the treehouse. The stash is hard to see against the wood.
Helmet -
I think this is a chest in one of the Broken Valley mini-boss areas, I think the one by Maxos' temple. Either that or the one by Broken Valley. It's not in the mine, though.
I don't remember where I got the leggings from, but I do remember that there's one piece in the
High Hall Mines - there's a chest beside some lava, and a key hanging in a cage. If you can get the key, there's a piece in there, but I think you did that already, because I think it was the gauntlets in there.
I'm also interested in finding out where the Cuirass and Necklace are, because I thought I had them, but I didn't. I hope I just forgot to pick them up somewhere, but I fear I accidentally sold them.
