I couldn't find a 12 inch glass tray anywhere (all the glass trays I found were either too big or too short) but was "lucky" to find AppliancePartsPro.com that not only had the part but had a diagram showing the actual part #.
I ordered the part, and was delighted on how quick I got it. It was very well wrapped so it couldn't break.
I placed it in the microwave and it fit perfectly! I saved a LOT of money since the microwave is multifunction and very expensive to repair.