I seldom go to O'Reillys or Auto Zone without a printed list of what I want.
Years ago I was after a fuel pump for the 400 I had in a 62 1/2 ton. I made the mistake of telling the kid what the engine was so he tried to sell me one for a 71Caprice Classic station wagon, what the engine came from. I tried to get one for a 62 1/2 ton with a 283 but they were out of stock. I settled for one for a 57 with a 283, same as 62 1/2 ton but I didn't tell him that.