Jim Carter truck parts has a tech article about 1954 GM trucks
1954 GM Transition YearIn 1954 and 1955 First series GM Chevrolet built basically a one off year truck.
1954 trucks were sold from September of 1953 to August 1954
1955 First series trucks were sold from September of 1954 to March of 1955
1954 and 1955 First series trucks are virtually the same truck.
There were a few differences between the two trucks, like the hood side emblems and the
1955 First series 1/2 ton truck used a open propeller shaft were as the 1954 1/2 ton truck used a enclosed torque tube.
1954 was the the 1st year GM used a full windshield as oppose to a split windshield.
1954 GM redesigned the dash and instrument gauges and front grill.
1954 was the 1st year GM offered a turn signal cup assembly under the steering column as opposed to the clamp on turn signal type.
1954 was the 1st year GM offered a electric windshield wiper motor as opposed to vacuum powered wiper motor.
1954 was the 1st year Chevrolet offered the Hydra-Matic Automatic transmission for their trucks.
Keeping it original will help it hold its value.
Its sad to see a rare one off year truck customized.
A 1954 truck stands out on its own because its body style was only built for a year and a half.
More info at link below
The Advance Design Spotting GuideThe first thing I would do is check your title to see what the VIN number says.
Some states used the ESN (engine serial number) on the title and some states used the VSN (vehicle serial number) on the title.
(VSN stamped on plate, located on drivers side door hinge pillar)
If they used the ESN on the title and they replaced the engine, the number on the title might not jive.
Unit Serial Number Locations 
