What kind of transmission would fit in my car?

I have a 2001 Mitsubishi Diamante Ls, it has an automatic transmission in it as of now. I am wanting to put a manual transmission into it, but not really sure how to go about it or what kind would be best and fit for my car. Any advice and help would be greatly appreciated. Thanks.|||It's not worth the time, expense, and hassle. The car is worth less than the conversion. Besides, I don't think Mitsubishi has a transmission that is applicable for the Diamante.