I ordered the rear half of the case for my Pro-96 from a local Radio Shack back in 2004 after I dropped the thing. I would imagine you might still be able to get parts through Radio Shack.
If not, I also suggest contacting GRE directly. I needed an antenna for one of my old Pro-2006 scanners and Radio Shack told me they could no longer get them. I emailed GRE and was told there shouldn't be any problems getting one and they actually contacted Radio Shack for me and made sure to send some more of that part number over to them. They then provided me with the correct part number to use when I went to Radio Shack to order one (I ordered two in case I break another one).
I really give the thumbs up to GRE customer service.