"My truck appears to have come with (RPO 3100) "

What is RPO 3100 - here is the list of 1954 RPOs.

RPO 314 was the Hydra-Matic transmission (available as an RPO on only 3100 series trucks - any model).

If you 1/2 ton truck is a pickup, all pickups would be a 3104 series/model truck (no matter what options/accessories were installed).

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.