HL I dont think this is a mismatch,the last 3 digits on the frame and engine are the same which seems toomuch of a coincidence,although I think engine and frame numbers are meant to be exactly the same(mine are).Was talking to a mate the other day and he reckons they did lots of different sorts of combos depending on what was available to them at the time of assembly.This looks like an excellent bike and a pre75 weapon as holeshot says.