Recommend you go to www.cadre.org Then to the EM serial number section. You will see lots of EMs and be able to get a better idea based on your serial number, etc.. I have seen corsa extras made from SLX (many) and 1 that was reynolds 753. The frame with the full chrome seat stays is rare to the best of my knowledge. My buddy once told me there was a way to tell if it is SLX by rubbing the inside of the BB tubing but I don't recall the key to identifying if it is SLX. Enjoy the ride.