You can put any tranny to any engine. The determining factor to what tranny you can fit where is going to be the chassis and where the outputs will be located. The problem I see with this project is whatever chassis you choose, your stuck to that trucks front and rear ends especially if you run with an MGT chassis because everything is connected as one peice and the a-arms and all that mount directly to that one chassis peice. If you are going to do something based on an already existing chassis your best bet would be to start with a roller and use that as the platform and call it what it is. If you want to build something from the ground up I would choose what diffs, tranny, front and rear ends and then have a custom chassis built around that stuff. Not to sound negative, but it will be almost impossible to mix somethings like a savage tranny with and LST chassis and so on.