I own a 55 Cameo, and there a couple of things that can help identify the truck. According to all the articles I have seen published, and I have owned my truck since 1969, all the Cameo's were made in Flint. Although the small window Cameo is rare, GM made Cameo's and Suburbans ( the GMC version) in small numbers that had the small cab rear window. The inside cab of the Cameo will have the deluxe heater, with the deluxe heater control ( which looks the same as the control from a 55 Chev car ). The above poster is correct when he states that the trucks came standard with the chrome grille, bumpers, and deluxe style hubcaps. Other than that, there is no difference.
There is a club for Cameos starting up again and I will look for the information.
Bob