Is it a sin to want to be an organ donor - before I die?

I mean, I would just love to part out my body like a '72 Chevy. I just know that someone out there could make better use of my parts than I am. Maybe they would actually be happy (something I continually struggle with). Do you think the obvious good I would do by donating my organs would outweigh fact that it would be as a result of my voluntary demise?