from
http://www.popularmechanics.com/home...er/print.phtml:
"For a retrofit installation, a 2- or 3-piece model is best. Usually, access to a bathroom is limited and a 1-piece unit will not fit through a normal bathroom door. A multipiece shower can be brought into the room in sections and then assembled in place, thus eliminating the need for what can be extensive demolition work. "
If the drain hole doesn't match, can you replace with pvc and make it work?