I own a 2003 All American Blue Bird and I love it so far. I bought it for only a few hundred dollars, but it needs a bit of work. In this project, I have three major phases: get it to run, gut it, build in it. I'm almost done getting to to run and almost done gutting it, too! The biggest part to get my bus driving again is a transmission. There, currently, is no transmission in the bus and I'm not sure what transmission I can use. From what I can tell, my bus is from the A3 series. It is also rear engine.
I've been told it's either an Allision MT643 or an Allison545. I was also told it has a DT466E engine.. but both of these suggestions are from Reddit. I'm hoping to get more of a solid answer from the Skoolie forums.