Identification of unknown peltier element
Compare it to a number of commercial 40 x 40 x 4mm TECs and your sample will probably fall in the middle somewhere. You won't likely be able to determine if it is a high-temperature type non-destructively.
Alternatively, have your accounting folks search for a few key words and see if it pops up on a Purchase Order. In particular, have them look for POs from (or mentioning) the company you suspect. It may be a discontinued item.