Can't help on the dig, but there is a black glass "hockey puck" ashtray out there that lists the Silverbird, Silver City and Silver Nugget. A quick look indicates that Major Riddle bought the Riata and changed the name to Silver City. Another quick check says Riddle bought the Thunderbird and changed the name to Silver Bird. Quick check #3 says Major Riddle built the Silver Nugget.

Can't find a scan, but I'll look for a picture. I'll get back to you if I find one...wish me luck!