There are many sizes of buses to choose from and each size fits a different need. For me, with my intent to make this my full time residence, I wanted to make sure that I had enough space for me and at least one other person (and my cat). I wanted it to also have headroom and be capable of towing my car. This eliminated all but the 12-window and 14-window carriage. The towing portion led me to search for the largest engine that I could find standard as well so I wouldn't have to worry about weight. Weight is one of those considerations in RVs that leads to compromises in construction and/or materials. I didn't want to make compromises in a structure that I'll be living in that will also hurtle down the highway at 65mph. One other consideration worth making when you're purchasing your bus is that you'll want to try to get one from before 2004 when new environmental legislation required computer systems to maintain/monitor diesel emissions. This can not only hamper the performance of the bus, but can make it very difficult to repair yourself or relatively cheaply at a mechanic.

I've got a 7.3L International Turbo-charged Diesel Allison with a DT466 all-mechanical transmission. This is possibly the most produced and most durable diesel engine in existence. Every workshop has parts on hand and every mechanic trains on this engine. I spent a lot of time digging through school bus driver forums and diesel truck forums and settled on what worked best for me. My advice for most potential bus purchasers, however, is to avoid any standard gasoline short buses. You’ll find they are severely underpowered and they guzzle gas. Unless you’re just getting a weekend warrior, you’ll wish you’d have gotten a bigger bus with a bigger engine.