A little more Information.
1 - The 1946 "First Design" were called interim trucks. They are a continuation of the regular 1942 models . They are not Post War trucks. The reason there is no data book is because you use the 42 book. The OS and OR base trucks came with a 216 engine BF or RPO 235 BG. The COE came with a 216 engine BJ or RPO 235 BL.
2 - The 46 4400 trucks have a max GVW rating 13000 and the 42 have a max GVW rating 14000.
3 - Going by the Assembly Plant code 20 and month code 10, both MDReed's and TwinstickOS's trucks were built at the Van Nuys plant in October of 1948.
The Van Nuys Assembly Plant open on December 1, 1947.
