Look for a two letter code stamped in the underside of the BB shell. You may have to move the cable guide to see it but on my '99 R4000 it's visible without moving the guide. The 2 letter code will at least pin down the year of manufacture. My guess is that it was sold as a frameset. Another possibility is that it was painted for a dealer's team. I have two frames that were painted for Helen's Cycles teams. One has Team Riley paint, the other Helen's Cycles. Neither are colors shown in the catalog. R800 was generally a Shimano 105 bike, so it would be reasonable to call it that.