mystery block solved

[DanielRobert]

Since it seems like I read a lot of posts with no answer to the particular problem(not on this site) , I figured I'd update mine.

I have a 1975 440 block....pistons are factory slugs with an obsolete part number but definitely have the Chrysler star on the inside of the piston. But they are big.....020 big...and so is the block.  Seams that Chrysler bored out some blocks and when they did, they stamped the block to i.d. it.  Sure enough, mines stamped with an A which was the code for a .020 block and pistons. Who knew?!

[Alaskan_TA]

I have not seen any TSBs yet, but the 'A' is mentioned in the 1974 TSBs.

http://www.hamtramck-historical.com/images/TSBs/1974/25-01-74D%20page6.jpg

[John_Kunkel]

The stamped oversize/undersize codes date back to at least the fifties....fairly common knowledge.