The shortest distance between two points...

[Alvin A Klusman Jr (Torque)]

NOTE THAT THE PISTON HAS BEEN NOTCHED ON THE "3RD PORT SIDE". This changes the piston port timing from that of an un-notched piston. Also you need to check the piston skirt legnth to see if it is a stock piston or a stroker piston. Stroker pistons are 0.080 longer skirt. Either one works on stock 1.50 stroke engines, but only a stroker piston doesn't freeport the exhaust ports on a 1.625 stroke Mc-10. If it is a stroker piston, the notch could be to retain the stock piston port timing. If it is a stock piston, the notch has changed the piston port timing from the stock timing. Best Regards "TORQUE"