Year specific dampners?

I had mine redone by damper dudes, you say that you have 3 months to get your build done, it only took about a week and a half round trip. And I sent in 2 dampers, my /6 one and my son's 318 one at the same time. There's another company, damper doctor, never used them but also in California, haven't heard anything bad about them. Both would be them rebuilding your original one. On both sites they show pix of various dampers by their in house part number system, and I seem to remember an industrial slant damper that has 3 belt grooves cast in, it was pretty salty compared to the normal car/truck one. But then again that's what you'd have to send them as a core to begin with.
Regarding cars and trucks, as I remember, there are only 3 dampers used over the years. 2 for cast crank that differ by where the timing mark is, as Mopar changed the location of the timing mark on the cover and 1 for cast crank models mid 76 and newer.