Radio delete plates are the same for 55 and 56. The radios will fit 55 and 56 with the only difference being the colour of the knobs, 55 are black 56 are ivory. The 56 knobs are harder to find with out flaws as the material was more brittle with the knobs either cracking or breaking apart. The powerpaks that accompany the radios are the same except the Wonderbar powerpak is unique to that radio.
Thanks 427carl for the radio delete your courier (wife) dropped off! You didn't say how much you wanted for it. Let me know! Looks good, should fill in the empty radio spot just nicely