Going by memory here: the 58 frame does need to be modified to take the front clip of a 55-57, but it isn't extensive. I believe it is something simple like cutting off 2" from the front and drilling a couple of holes is all. Yes, 55-57 frames are the same and the Cameo is not differentiated in the frame. I do not think the Cameo has unique serial number either. Note my 56 frame is serialized (right behind the steering box) and presumably so are the later model years. A knowledgeable person may observe that your frame # and the VIN on the A-pillar are not the same. I don't believe 55.2 frames were serialized, so you will need to decide what to do if this is your situation.
