The joint for the caps is cracked at the factory.----I believe these rods are plated before heat treating.----Perhaps stain marks are confused for cracks.
???----When I look up the 56 cube pistons in an aftermarket book, they are the same from 1886 to 2001 ??-----Why would you compare a 1993 listing with a 1995 ???
Marketing 101-----Build the same basic motor in 3 versions.-----as 50 / 60 / 70 HP.----Same displacement.-----Pistons all the same.-----Tuner the same-------Carburetors different.----Simple as that.