Finaly got done with installing a filter on my 15 model GMC. I posted a write up on gm truck forum and I'm just gona simply copy paste it here. This is my original post asking you guys about doing this: https://bobistheoilguy.com/forums/ubbthr...L80#Post4451609 Here is the what all I did and how it turned out, Pictures, I'm used to photobucket, but they decided to start charging people. F that. I'm using Google docs for the first time. Hope it works. After changing out ATF in my '15 model truck, with~35k miles, I decided to install an external filter to help better manage all of the debris, shavings, wear particles inside the transmission. There is no way it can be good for precise piece of hydraulic machinery to run fluid that is so contaminated. Cleaning off that magnet inside the pan, one has to wonder if the internal filter is anything more then a rock catcher .The amount of trash that clings to the magnet in just 35k miles is ridiculous. And that is only a ferrous trash, stuff like: aluminum, clutch material, brass and so on that doesn't stick to the magnet, is still suspended in ATF floating about plugging stuff up. I have never seen same mount of [censored] in engine's oil pan, never. Meaning that engine's oil filter is doing far better job then an internal transmission filter. Here is what I did. After looking at what others have done and taking my time thinking this problem over I decided to install filter next to the windshield washer fluid reservoir/tank. This location is very convenient for several reasons: lots of room, filter changes will be easy, I can keep an eye on the leaks, easy to tell if filter and tubing are getting hot (meaning ATF is flowing), very little new plumbing, and I can easily convert it back to stock because of no permanent modifications. https://drive.google.com/file/d/1SzJ0tgLwWpajDNE1BMboTy5RXBkbgm33/view?usp=sharing https://drive.google.com/file/d/1GH2_yX4u5Gw7qQBkldfqUOjGXDDINCWU/view?usp=sharing https://drive.google.com/file/d/1sgar-Wn34ormQokTkNCA3oiQJe4xB3uj/view?usp=sharing https://drive.google.com/file/d/13AoesVdin0ONs-hdQoLUX9fzlYqALvU3/view?usp=sharing Then I had to figure out for sure witch way fluid flows through the coolers. What got me confused is the fact that manual shows fluid comes out of the top port and goes back in through the bottom. But a member on here did an external filter set up similar to mine and he swore that the flow is in revers direction from what book says. He even started his truck to verify for sure. FL335i I'm not out to bash you, I'm simply pointing out that your post had me all jacked up and I hope you don't see it as an attack on you. Here is a link to that post: So I decided to verify on my own. Took the thermostat off the transmission housing. Put it up in the vise and ran air through it to see just what the heck is going on. When thermostat housing is cold, air would come in through the top port ( transmission side ) and out of the two bottom ones ( cooler port and transmission port). No air out of the top cooler port. Heated up the thermostat housing and flow changed. Air comes in through the top transmission side port and out the top cooler side port. No air out of the two bottom ports. I attaches two horrible hand drawings to hopefully help you understand what I'm blabbering on about. This would also explain why member on here got turned around and thought that book was showing a wrong direction of flow. When transmission is cold and thermostat is closed, taking off one of the cooler lines will make it appear that fluid is moving in the opposite direction from what manual says. Again, hope my chicken scratch drawings will make sense. https://drive.google.com/file/d/1OHH7bJzxf_-W-vR5lRn349JWL_YjaEBP/view?usp=sharing https://drive.google.com/file/d/142WCOv_5jVuuZWIP7RFxVnN257m_R8ZH/view?usp=sharing https://drive.google.com/file/d/1B0Ew7p-V0e49fcIkLEZXgFdo8mOMCJCk/view?usp=sharing Now with all that out of the way I used Derale 130005 remote filter mounting kit. Fabricated a bracket to hold the filter high enough to fit Fram #3614 size filters and give plenty of room during the filter change. Used 1/8 inch think by 3/4 inch wide piece of hot rolled that Lowe"s sells. If I remember right bottom leg is 6 inches long, vertical is 6 inches tall and housing mounting flange is 2 and 3/4 inches wide. My horrible welds are just that, horrible, but should be ok to hold up that fram. In the words of AvE " Grinder and paint, make me the welder I an't." https://drive.google.com/file/d/1ahaJ9Na-803kYP5_49YJUlco0eTqLaCk/view?usp=sharing https://drive.google.com/file/d/1HNxarJaBRZ4cMfUtpZMMO8cAVUQTTgDJ/view?usp=sharing https://drive.google.com/file/d/1ZyzN61RKMoOMWsZzcegZZaFDG0NIr1Ue/view?usp=sharing Now for pluming I decided to stick with GM original transmission push connect 3/8 inch transmission line. This is an expensive way to go about it because I had to purchase a hydraulic press/dies in order to form 3/8 GM transmission connection. Its a Mastercool 72485 flaring tool set. If you do buy one make sure it has GM transmission line forming die set. There is a cheaper version of this kit # 72475 that does not have a needed die set. Just a heads up. I used cheap tube bender from Lowe's, holly [censored], its difficult to make a proper bend using that POS. Now I know its a poor craftsman that blames his tools, I'm just letting you know to be ready to redo lines several times if you use that style of bender. Also you will need two (2) 3/8 inch NPT to 3/8 GM transmission line fitting/adapter to go into the filter housing. I used Doorman 800-606, got it on Amazon. Local parts stores sell them too. Line I bought at Advance auto parts part number #CN-660, worked great. Those are 3/8 inch OD and are 5 feet long. I went through two of them. If you know what you doing one is plenty. Also don't use the thick stainless tubing Amazon sells. It wont form correct in the die. Plus its a major pain to bend using Lowe's bender. Ask me how I know. https://drive.google.com/file/d/1SsEWBva_lfiN3D9nC7AeivuH69kWhYTr/view?usp=sharing In the above picture I took tube number 14 out and hooked up mine as shown. Keep the old tube just in case. Started up and what you know, no leaks, great, so far. Let the truck warm up and keep looking over all the new connections, check under the truck where i have been dicking with thermostat, all good. Take off down the road. Temp outside is ~30 degrees, drove for 10 miles, pull over to check on the connections and look for leaks. Everything looks great, however lines are cold and filter is cold too. I figured no big deal sense transmission is only at 135 degrees at this point and thermostat is still closed. It took transmission about 20 miles to come up to ~185 degrees. Drove around for 5 miles after it warmed up to make sure let all the lines fill up, let the fluid circulate and if there is any leaks let them drip to be easier to spot. Pull in the parking lot, open the hood, lines are hot, filter is hot, everything looks dry and thermostat is dry too. Headed back to the house, check it all over again, looks great. So that is how I did an external filter on 6L80. I'm leaving that orange Fram until next oil change , which is in~3000 miles. Reason for short run is because I want to cut this filter open asap for my own curiosity and didn't want to waste an Fram ultra on such a short run. Then it will be a Fram ultra and probably run it for two years, which is about ~10000 miles on this truck. Will also do cut it open as well.