Go to O'Reilly's with your VIN and have them give you the filter according to the VIN. If you go to other auto parts stores with just the standard make/model/year information they may offer you several different filters. I experienced that first-hand.
It's a messy job as
@B E N indicated. I used three drain pans and still made a mess. It takes way, WAY more replacement fluid than 4 quarts. Whoever told you that has never done it. As to the shop who told you that the trans has a lifetime filter, he lied to you. They just don't want to get their hands burned.
There is a real technique to it, too. First off, you need a glove that you don't mind sacrificing. The "dipstick" if you can call it that is so close to the exhaust system that you will absolutely suffer third degree burns if you don't wear a glove, and you will get burned anyway - just not as severely - if you do wear a glove. The last time I was down there I used a glove with five layers of duct tape wrapped around the knuckles and I still got burned.
There is a cold fluid level test and a hot fluid level test. Both require you to be under the truck while it's running. You fill the transmission with a certain amount of fluid, start it, run it through the gears, and then with it running you check the fluid - the cold test. Then you add more fluid and drive it until the transmission comes to full operating temperature and check it again - the hot test. If you don't get burned doing the cold test you will get burned doing the hot test.
At the mileage you posted your truck's transmission is way overdue for service. I did mine at 45,000 miles and I was very glad that I did. The fluid smelled burned and was quite dark, and there was particulate matter coating the inside of the pan and the outside of the filter.
