No I had not heard that claim. I will look and see what I have for VIN's. My understanding is the Riviera doesnt have its own distinct VIN and is intermixed will all the big cars built in Flint. What is your build date Tom and Chris?
My build date is 12B. From what I remember it was mid December of 64 when Buick changed from the small to larger GS emblem so maybe I have one of the last small emblem cars. Skylark GS' went into production in Jan. of 65 I believe but I don't remember when it started with the Riviera Tom