From:Robbie e-mail:tls-A-newmex.com
Subject:RE: serial number ? Date:Tue Dec 4 18:28:56 2012
Response to:18022
The engines were assembled and stamped in families, so the numbers include the other versions of the same family group. So the STUs are included in the family, making numbers run higher.

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Aloha from Hawaii. My 1956 st has a serial number that does not seem to be in agreement with the information you have posted. The number on the engine is very easy to read and is 56st3222. The highest number, because of the number made, should be 3219. Anyone have any information that can shed light on this.