Well, i modified darth sion's head en everything looks ok but one thing... The eyes appear on the forehead!!!, i think it is becase i moved down the eye socket... but.. how can i put the eyes where they should be!!?

they have the right position in gmax and you used taina's replacer-tool to convert the files for the game, I assume?

well, head-models are a damn tricky thing. taina's replacer can only handel simple vertex-movements, but no movements of helpers and such things (dunno about animations).
to get such stuff changed, you have to use mdlops to recompile the mdl and mdx files. but if you do that with a head-model, it'll float on the shoulder rather than be attached to the neck.
the only way to get that fixed, is a naaaaasty hex-edit guessing-game which only a few modders ever managed to do a handful of times, afaik.

Hex editing... Wonderful....
Well, at least now i know what was happening....