Hy TonofFun, according to my truck sales data book for 1959 "Apaches are series 31 to 38. Medium duty Vikings consist of Series 40, 50 and 60. Heavy-duty Spartans include Series 70,80,90 and 100. Series 50, 70 and 90 are Low Cab Forward models, sometimes abbreviated as "LCF" models." Hope that helps.
