The pistons are manufactured seperately from the block... they aren't "made" for THAT block. there are going to be some varianced in piston size, etc.
So, they get all the pfinished pistons together and mark them with "grades" 1, 2, 3, etc. those grades reflect which size it took to fill the cylinder the best. If you were to purchase his pistons (6 of them) it wouldn't be INCREASING your odds of fixing the problem. you'd now have to have 6 pistons that ALL ended up matching the same grade as the piston(s) you are replacing.
The only thing that buying all of them would do is increase the number of potential grades you could choose from, in hopes to match.
Just call Bill J, tell him your year, see if they even OFFERED a grade difference that year, and if not you can order then. if so, you need to know the difference, by looking at the number stamped on the piston head.
