Saw some talk about these earlier but can't find where it was. Some mentioned they were hard to find. This guy has a bunch ready to go if anyone is looking.
http://cgi.ebay.com/CONDAR-FLUE-GAS...emQQptZLH_DefaultDomain_0?hash=item2c51f17608
http://cgi.ebay.com/CONDAR-FLUE-GAS...emQQptZLH_DefaultDomain_0?hash=item2c51f17608