Drillbit,

From 1940 to 1957, the serial numbers included the year. The first two digits were the year. This is for gas and electric trucks. If they were warehouse lifts and worksavers, the year was the 2nd and 3rd number. Also, the serial numbers were only 6 digits. I would check for another number somewhere on the frame. If you have a floor plate, remove it and check just under that. Depending on how much paint is on the lift, may be hard to find. Check the frame just above the transmission. A picture would help.