My 460 has pistons in it that are federal mogul I think. speed pro or sealed power and the bottom of the piston has 516 99 on it cast into the bottom of the pistons. I an not sure of the number sequence I will clarify it in the morning but the numbers are 156 followed by a 99 spaced away. The 99 I'm sure about but the 156 might be 561 or 651 or 165 or 516 and so on. I will clarify this tomorrow but they are the piston that the machine shop put in and I was just curious if these numbers could tell me what piston these are. All 8 have the same number, in the same place. If anyone could tell me, it would be awesome I don't plan on changing anything I was just curious. I will confirm the numbers tomorrow but the first 3 are the 1 the 5 the 6, in some arrangement. Thanks and have a pleasant weekend.