Bruce is correct regarding there being at least two sizes of emblems. In the Master Parts Book there are three different part numbers for 47-53 front emblems.

The MPB lists:
#1 for COMM (Commercial 1/2 ton through 1 ton)?
#2 for D-D (Dubl-Duti, Forward-Control Chassis - used for non-GM Step Van) and UTIL (1.5 and 2 ton trucks)
#3 for COE

two different 1954 emblems (from an old article by Bob Adler)

The 1954 COE emblem was mounted an on special base, as is the earlier emblem on a COE.

Step Van - built on Dubli-Duti chassis