Markings on top of my pistons/what do they mean?

[70 RAG TOP]

  :feedback:I was just curious about some markings on my old pistons?  They are flat top style and have  B C D marked on various ones.( 5-C's, 2-B's and 1-D)  I read something that said these were marks indicating different sized(be it a fairly small difference) cylinder bores.  Q1-Would this indicate that these were the "original" pistons that came in this engine from the factory?  Q2- Could this have been the cause of my varying compression readings on my engine before it was rebuilt?  Q3- Why would there been a need for different size pistons(were the manufacturing processes back then that erradic)?

Also, There were 2 crescent shaped depressions on the top of each piston.  Was this from the valves hitting the pistons or is this something that was there from day one?

thanks

[burdar]

Those crescent shaped depressions are valve relief notches.  Those were built into the pistons for valve clearance.

The letters you found could very well be factory markings.  I know they used letters on the side of the block to indicate size differences.  They could have done the same thing with the pistons.  Check out these two pics.

http://board.moparts.org/ubbthreads/upload2/4508360-OEGold1999024.jpg

http://board.moparts.org/ubbthreads/upload2/4511333-DCP02510.JPG