I wonder if this was a change between 47-54 MY and 55-beyond MY?
MY=Model Year - for Chevrolet and/or GMC trucks?
Then, in answer to that question :
- 47-54 MY : (47-54 Advance-Design Chevrolet trucks and 47-54 New Design GMC trucks)
-- there were many changes in the several MY between 47-54
-- there were very slight differences between the 1954 Model Year and the early 1955 Model Year.
- 55-beyond MY (1955-1959) - there were two 55 Models Years for Chevrolet & GMC trucks:
- the earlier 1955 & the later 1955 - for Chevrolet and GMC trucks
1955 Chevrolet Advance-Design to the significantly different 1955 Task Force Chevrolet trucks; and,
1955 GMC New Design to the significantly different 1955 Blue Chip GMC trucks
