In our area, any big block truck was pretty rare, we didn't have as many as some areas were blessed with.

When I was messing with big blocks in trucks, it was during my dirt track days (late 70s through about the mid 80s), what motor bracket came on what year truck was not of any concern of mine, my concern was that the brackets I had got the motor close enough I could make them work. It was easier to modify existing truck motor brackets to fit our need then it was to modify car brackets to work. Then we need to throw in the fact that there may have been 3 or 4 small block to big block swaps over that span of time.
Now we add in all those years since the mid to late 80s and you think I should trust my memory with any kind of certainty on these kind of things?
Good luck with that. Gene