i knwo i should probably go to a Grand National message board for this question but i dont know of any..

does anyone know of ANY manual transmissions that can be mated to a 3.8L turbo buick motor???
(at least 5speed, if not 6??)

 

It can be done, but you'll never see anyone do it because it will just slow the car down. Take it from a three time turbo Buick owner, the original trans is the best option. It can be built to handle whatever power level you need. You can ask at any of the GN sites such as http://www.turbobuick.com or http:/www.turbobuicks.com, but they will tell you the same thing.