Thanks to all for the replies.
According to the very nice MDPD Detectives from the Auto Theft Division who are helping to get this sorted out 55 shows as having a stamped frame. I explained there were 2 different 55's built and they're gonna do some more research.
This evening I took the drill with a wire brush to the top of the frame, drivers side, from the front shock mount back to past where the e-brake crossbar is located. No indication of any stamping.
In answer to Tim's first post.
Engine ID 030I343F55Y
VIN H55N004775
Last Registration What "code" are you referring to?
Another question re engine serial #'s. Are all 216, 235 & 261 blocks stamped in the same place?