What is interesting is finding items today, mostly accessories and structures though some rolling stock as well, that were evidently marketed during what I termed the glory days, yet despite being active in the hobby back then, I don't recall seeing them! And I used to study each and every catalog! I can only surmise that some items were released through limited dealerships, or I just missed them, or just don't remember!
It sure is fun discovering neat things made during those years that I can use on my layout. FWIW: the easiest method to find when an item was made is to enter the item's number in a Google search. This will give you a nice history with release date. Obviously, this doesn't work for K-Line and Weaver items. I recently discovered some wonderful brass structures that Weaver had made during the glory years, yet researching their origin was not so easy. I eventually found someone who had made pdf's of Weaver catalogs - good work! K-Line also made some wonderful and realistic operating accessories in the glory years.