The 66 was based on the Falcon, where as the 67 is based on the Fairlane, the difference being front end sheet metal as well as the dash inside (don't quote me on the dash thing) I belong to the Fairlane club of America and have one back issue that has a 66 that was Fairlane based and apperantly the only one built that year the rest were Falcon based. I would love a 67 XL big block to match my 66 big block GTA but I also would have to sell my 69 swb.