A "VIN" code on the frame became standard/required in 1956. A 1955-2nd truck/frame might have been within that "requirement window"?But, here is that info in the 1955-2nd Shop Manual

The online 1956 Truck Shop Manual is missing pages.

I am pretty sure that the 1956 Truck Shop Manual has a reference/image for a code on the frame. I showed that documentation/Shop Manual to the NC DMV inspector when he mistakenly told me that a code was placed on the frame in 1954 - he was incorrect and he was interested in seeing the documentation (he sent photos of the documentation to Raleigh).

Tim
1954Advance-Design.com
1954 3106 Carryall Suburban
1954 3104 5-window pickup w/Hydra-Matic
The 216 and early 235 engines are not "splash oilers" -- this is a splash oiler.