Yeah, I'd remove the heater and leave it out of the bus forever! That thing runs off of antifreeze that's pumped from your engine. If you build the interior of your bus and that thing springs a leak someday, it will be a disaster! Antifreeze would be pretty easy to clean up in a regular bus interior, but it will NEVER come out of stuff like wood, mattresses, carpet or anything else you're going to put in your bus. I removed mine. It was a very messy job too. I'd do it now before you get too into converting your bus. If you do decide to keep it, you could grind the current screws off, and then just reattach it to the floor using some TEK screws. But seriously, that thing should go. The only time that heater will work is while you're driving the bus. It would be WAY too expensive to idle your engine to keep that heater warm. You can get a propane furnace real cheap for a bus that size. Then you can run it while you drive down the road. If you do have wood under there, you could get a circular saw and just set the blade depth to like 1/4" or so to start. Then get a big wrecking bar and start prying it up. If it's just rubber on metal, then do what I did. Hammer and chisel. In my opinion, that heater really needs to go. I know a few people have left them in there, but it's not worth the risks and the hassle if you ask me.