RivNut, thanks for your reply. I have read other posts by you on this forum and I value your opinion. I understand everything that you are saying. But could the car have been custom ordered with the single 4 barrel engine? I did not check to see if the transmission was BS coded. Does the plaque mean anything? Have you seen other Rivieras with that plaque? It was about 1 1/2 inches long by 3/4 inch wide. I did not take a picture of the plaque, otherwise I would post it. Regardless, it seems to be a somewhat rare car with the 425 engine and vinyl top.
Jim