I have a Cougar 318SAB, and I installed a new pin box this year on my 5er. I knew from the 5er that the pin box was a Lippert 1621. There was a tag on mine that identified it as this. But I wanted to make sure before I ordered a new one from Tweetys. I checked the application guide that TrailAir provided for measurements on the existing pin box. I used the dimensions furnished to verified that I had the correct model number for the Lippet pin box.
You can also use this same method to verify what pin box you have on your camper. See the attached link.
http://www.trailair.com/products/airpin/ap_appguide.
Jim