The serial number is found on the (data tag) located on the exterior of the transmission housing.
The serial number itself is not decoded (no hidden model info), but when looked up in Allison’s system, it returns: Allison Transmission Serial Number Lookup
If you’d like, provide a clear photo of the serial number plate (or type the S/N) and I’ll: (a) show how to enter it for a warranty check and (b) list the next steps to get parts or service for that specific unit. The serial number is found on the (data