Only about 2,800 Land Rover Defender 90s were federalized for U.S. buyers during the mid-1990s as North American Specification, or NAS, trucks, and clean, largely original survivors are getting harder to find every year. Chassis #2094 of that run, a 1997 Defender 90 wearing AA Yellow paint over gray upholstery, is currently up for bidding on Bring a Trailer, where the auction has already climbed past $70,000 with bidding still open ahead of an A…