The 54 Hydra-Matic truck engine is different from the '53 Powerglide automobile engine. The '53 Powerglide has hydraulic lifters and a 2-bolt valve cover. If someone has the '53 Powerglide engine matched up with a '54 Hydra-Matic transmission, the engine might be painted blue (if the Powerglide paint is still on it) but most bets would be on the engine being a later replacement to the original 235 truck engine.
The 1954 Chevrolet Truck Engineering Features book, that describes the new 235 truck engine and the new Hydra-Matic Transmission, describes all 235 truck engines (Thriftmaster & Loadmaster) as being gray.
