Do you have a picture of the back stamp? If so, could you post it please? Are there any other markings on the back of any of the pieces?
Looking forward to hearing from you,
This is Stetson pattern number STT181.
I did not find any available pieces at www.replacements. com. Here is the link to their site: http://www.replacements.com/webquote/STTSTT181.htm