back40mc said:I have just begun to restore a 1972 cl450 and your posting appears to have settled one issue that I had. My frame and engine #'s do not match. They both fall into the series suggested by your posting, but the last two digits are 28 apart. Is this normal? I had assumed that the bike was a k5, but my frame number preceeds the 50008489 number in your posting. I am not sure if I have a mismatched engine/frame, or if this is normal for the year and make. Any help would be appreciated.