First went to the Hayden catalog and found the replacement pn - 2705 (std duty) / 2747 (heavy duty). Then I measured what I had in the car because I have no idea what was put in by the previous owner. It was the "correct" length, and I needed between 1/4 and 1/2" more fan height to get the fan 50/50. I matched up all the other dims and ordered the 2731 heavy duty from Summit. 77 to 82 8 cylinder Caddy is what Hayden lists as the original application. I think most big box auto parts stores carry Hayden, but Summit is easier and it just shows up at my front door in a couple of days.
