Ran into my first major problem today. Removed the plywood floor and found this. What a mess. Not sure how I am going to repair this yet.
Apparently the schools just hose out the buses when they need cleaned with no regard to what that water will do between the wood and steel floor.
Most of this area is above the cargo area. The underside in the bay looked good. I hope that when I get the wire grinder on it it will be better then it looks. (edit: it wasn't)
If you buy a bus in the snow-belt you most likely run into this same problem. The only way to avoid this is to buy a bus from the south.