Just purchased a 1948 Chief that was supposedly rebuilt: don't believe it! Looks like someone may have put in new Robbins M-1500 pistons std. size but used old rings and didn't hone the cylinders! The good news is there is virtually no discernible wear (out of round or taper) on the cylinders themselves. The pistons look almost brand new with the "std." marking on each crown found facing toward each cylinder's intake valve. Question is whether the orientation of the pistons is correct. These are solid skirt pistons.....no T-slot or apparent offset....so I'm wondering if orientation really matters. I hate to take for granted that the previous owner/rebuilder did things right and simply follow their mistakes.