Reggie,

The SuperTigre 60 cc Twin was introduced in 1986. There were some difficulties with uneven fuel feed between the two cylinders. They changed the rear crankshaft portion in 1988 to even out the differences. Any of the engines made after that would have the "newer" rear crankshaft piece.

Unfortunately, an external inspection will not tell you if your engine was made befor 1988. Most of the engines still out there and running, though are ones made after that date.

The stock number for the rear crank is:

SUPG3303 22012474 CRANKSHAFT REAR TWIN $57.99