I have a local MOPAR expert friend who recently bought a 77 NYB St Regis (white exterior, white leather seats and red interior trim). He has done wonders with it and is still improving it. I offered to decode the data plate on radiator support. I got almost all of them to make sense. On three different sites, I found that P51 means power sunroof. The car does not have a power sunroof but the VIN from the tag matches the car itself. Since the St Regis and maybe even then sunroof cars were done at third party coach shops so that the P51 code might mean special handling. There is a separate code on the tag which confirms the partial vinyl top associated with the St Regis format. Do any of you with St Regis (and maybe Crown Coupe before it) have similar codes but no sunroof. We assume he does not have a sunroof buried under that vinyl top and above the headliner but were surprised 3 websites with data plate codes confirm the same code for sunroof. No, he has not found the build sheet / broadcast sheet if the 77 models still had them like earlier MOPAR models did. Thanks for your thoughts and advice.