For most Tripp Lite products, the serial number will contain 18 characters consisting of numbers and letters other products may 12, or 13 characters . The serial number will usually begin with a "9" or "2". Serial numbers are often found on the back or bottom of the product unit. In some cases, the serial number .The serial numbers: X - numeric character. L - alphabetic character. Allis-Chalmers Corporation. Discontinued the manufacture of distribution transformers in 1975. mineral-oil filled transformers comply with the PCB non- contaminated guidelines. Transformers manufactured in other General Electric Company plants..Enter your True product 's serial number to view specific information pertaining to the cabinet..The manufacturing date is coded into the serial number not the model number of each appliance. Our serial numbers begin with two letters followed by six numbers. The first letter identifies the month and the second letter identifies the year it was manufactured. The corresponding letters for months and years are in the .