Excellent condition 644 Tigershark engine removed from a 1993 Tigershark which had the 644cc versus the 640cc but same engine with 18mm output shaft thread.  I do have adapters that will thread on the 18mm shaft so this will fit the 1996-1999 which had the larger shaft for an additionall $40.  Looking in the cylinders the pistons and cylinders appear to have no wear and no marks, must be a low hour engine with 136/135 psi compression in both cylinders.  This will fit all Tigershark/Artic cat watercraft with a 640 or 644 engine, like stated 1996 will require the thread adapter.