Hey bowtie, That ID plate No. starting with "HP" you gave, is indeed indicating a 1950 1/2 ton. If it's a 2ton, it should start with either, "TV"- 6100 series, 137in. wheelbase, "TW"-6400 series, 161in. wheelbase,or "TY"- 6500 series, 179in. wheelbase. On most(not all) '50 model trucks a series designation emblem was placed on each side of the hood under the "Chevrolet" emblems.
