Have you called them to see if it fits the hole in a 1954 GMC? The listing says 47-53 GMC. The 54 GMC and Chevrolet trucks have different radios and both radios are completely different from the earlier radios.
There is no speaker opening in a 1954 GMC dash. The speaker was mounted in a housing in the front of the roof. Jim Carter sells a radio speaker cover (RAS120 - $77.50, ugh) for the 1954 GMC.
The radio at the link I posted above, is the only commonly available GMC 54/55 reproduction radio that I have seen. In fact, I have never seen another reproduction radio that fits the radio cut-out in a 54/55 Chevrolet-truck/GMC dash.
