These arms are very popular with some of the hybrid conversions being done, I think that some of the TT500 conversons may have used them. Either way someone has taken away the through bolt system for the OEM chain guide and welded in the nutserts for a different type of chain guide and the original shock mounts have been completely removed with new one's fabricated and fitted futher outbound on the arm. There is also a diffrent style chain rubbing block and what appears to be a bracket welded to hold it in place.