Having worked at "The Big Yellow Mother" for 18 years I also bought this set. I can't remember exactly when, I want to say early 90's from a train store in Charlotte.
While I also heard the rumors, I never did see anything in print about the set being yanked from the shelves nor the number produced. As you mention there seems to be little documentation about this set using normal search measures. Hopefully someone will chime in with the info.
Bill, MTH has a nice tank car being delivered next month in the Kodak Chemicals Livery:20-96256.
Paul
ps - Dear MTH, you don't mind me asking again for a Kodachrome SP Livery in Premier...