Weird. The worst blocks I soniced started in the mid 80's and went clear into the early 90's. Those were the worst I have seen. Also, the casting at the paste lines were always horrible on those core. That doesn't affect performance, but people see it and get worried.
I can't find the sonic numbers from my X blocks. Every one was better than Chrysler called out. I have access to an R block that belongs to a friend. Maybe I should sonic that pig. Just so we have the numbers.
Which, now that I think about it, I can't post the paper work I have for the X and R blocks on the web. Some day I'll learn how and we can post that stuff and make it a sticky.