Pahaska had a 2002 22' CCD when they first came out. The first appearance of OSB was for this model IIRC. And I don't think it was used on many other coaches -- somebody might chime in on that. Here's a few pics of his OSB
and narrative when he put down his cork floor.
I think it was something like 2004 before they realized they had a big problem and discontinued OSB. Could be off a little on that. Do I recall at the end of the OSB experiment they even started building 22' CCDs with a membrane between the frame and floor and no belly pan?