There are still some Thrush sidepipes out there on ebay, but they aren't cheap, and they aren't in great shape

and something I didn't know, they aren't complete. From what I see on Ebay, they still need a chambered exhaust pipe to be inserted into these. So, there's a couple hundred dollars more

and with ordering from different sources that probably don't have any guarantee of money back satisfaction, you're taking your chances that these will fit.