5 RJ E 1306 is the serial number stamped on the data plate of a truck for sale on eBay. I usually can figure these out myself, but this one has me stumped. This much I think is correct: 5 = Kansas City R = 1948 J = 4100 E = May Right? This poor stakebed truck with dual rear wheels is being called a 3/4- or 1- ton. Thanks!