http://www.rctruckandconstruction.co...read.php?t=128
Here is a thread explaining Axle options without breaking the bank. There are grear reduction and transfer case options in the thread also. I think building a stock king hauler kit to figure out how everything generaly fits together and then take it apart and start working with a fresh frame is the best way to aproach it. Make a build thread in the truck section so all of us can see your hard work and we can help you!
Something like this?
Happy building and have fun using the awesome resources the forums have