Mike W. posted:The PWC Series Berkshire from the 2007 Set had the original PW tooling. Why was new tooling created for the Conventional Classics Version?
As JC642 said previously, "The original PW 726/736 die-cast body mold had its final run with the L&N Big Bertha Berk back in 1986. From then on Lionel's iconic engine was built with mostly new tooling."
That's what I always heard as well, that the original PW tool failed part way through the production run of the Big Bertha Berk. After that failure, it had to be reworked/replaced. There was quite a gap of time until the next Berk was produced, due to the time and money that was required in making a new tool.