MDReed More info on your truck. Chassis serial number 200S10 1314 breaks down as follows... 20 = Van Nuys Assembly Plant OS = 1946 first series 1-1/2 ton with 160" wheelbase 10 = Month (October) 1314 = Unit number starting with 1001 From Mike B
Your truck was built at the Van Nuys plant in October of 1948 The Van Nuys Assembly Plant open on December 1, 1947 So you have a “42” model built in 48.
As for the cowl tag, the only references I found to "MASTER" being a truck model is in the 1938 and 1939 data book. But below is a 1942 1-1/5 ton with 160” WB pre-war tag with MASTER printed on it. 9MS42 x237x hard to read. The 42 in the month position represent the 42 month (June of 1944) of the 1942 model production year. All civilian production of cars and trucks ended in June 1942. .