The MSH Advanced Set had one of the longest print runs I’ve seen in a TSR product. It was continuously in print – essentially unchanged – between 1986 and 1992.
Marvel Super Heroes Advanced Set [BOX SET]
1986, 1992 … Jeff Grubb … TSR 6871 … ISBN 0880383682
(I’ve got some print run data for the Advanced Set there.)
Comparison of 1986 and 1992 sets
TSR gave the MSH Advanced set a slight facelift in 1992. Other than updating the TSR logo to its then-current “Gold Badge” style and a lasso around the title on the box lid, the company seemed mostly preoccupied with updating the copyright date throughout the set.
This is a bit strange, as TSR was typically indifferent about updating copyright and printing info through the years. I’m guessing that this new-found attention to detail had to do with maintaining their Marvel license in this case.
Following are some comparison photos.