All water heaters have a Rating Plate that lists important data such as the model and serial numbers, manufacturing company's name, length of warranty, wattage of elements installed (on electric models), gallon capacity, input BTU rating (gas models), and more. You can determine the age of the water heater by de-coding the serial number. Navistar Engine Serial Number Location. Engine serial number for Navistar engines inscribes as stamped on the pad and it locates on the block. In case of Navistar engines, location is easy to notice. For any engines that were created before the year 2000, the pad is inscribed on the left side ofthe block and just below the parting line.
April & May 1980 Sample number 123 D A 123456 1st three digits are the Compressor Part Number. 4th digit is the month of Manufacture. 5th digit is the year of Manufacture. In this sample A represents 1980. 1980 = A 6th thru 11th digits represent the Unit Identity Number. This serial number style was only used during the months of April & May 1980.