There is a whole forum website for just that. 4btswaps.com. They could tell you all about it. But I've drove one with a 4bt in it. I took off down the highway and I was doin 80mph before I knew it. It was on 35's. It had stock AX5, yes AX5 tranny and stock axles. I'm pretty sure they don't even need an ECU to run. The owner of the one I drove said he gets 30+ mpg most of the time. He can pretty much idle up steep trails.