Based on the serial number the OP's frame was manufactured in December 1980, which makes it a 1981 model. Members have reported 26.2mm posts on frames with Araya 631 tubing decals. This is in the range of a lightweight hi-tensile steel. The closest Centurion model would have been the Super LeMans but at the time it was spec'd with a butted hi-tensile frame. It would also be close to a Nishiki Olympic 12 but again the Nishiki had a slightly better frame with a plain gauge CrMo main triangle. Probably the closest model was the Peugeot U010.