Bellows thermostat for tr3 and Metropolitan Nash Thermostat are interchangeable. There is a guy selling some NOS ones for the metro for 22.00 out of Kentucky on eBay. I think were made right there also probably back in the 60ites. I am not sure if he knows they are interchangeable with the English stuff. I bought one and they look ok, so I thought I would tell the forum. If I remember correct, the tr3 and metro rag top are the same also.