Somebody had the detailed write up and pictures for Sequoia way back on Tundra solutions using the tranny cooler lines. Bucket with lines for qty measured out. Put line into bucket, start the vehicle, pump out 3-4 qts, shut it off. Fill up 3-4 qts and repeat. The BG Fluid exchange machine did basically that, not pumping/flush. You would add 12qts to machine, one line went to return (to refill tranny) other line to waste container, start the truck and all done pretty quickly. Some guys did that with extra bucket fittings etc.
Toyota T-IV wasn't too expensive, only matching (recommended/approved) probably not certified was Mobil I think 3309. Supposedly they made the T-IV back then sort of like the Idemitsu thing. The Mobil was full syn from what I recall, not sure if T-IV was.
After that I had dealer do some fluid changes and one time they added BG ATC+ which totally ruined the shifting feel (like slipping). I didn't request that but they did it as part of the service. Multiple arguments with dealer service manager about it's not right, Master tech went for ride said normal, all sorts of deny anything wrong. My answer was so it was "not" normal from factory for first maybe 40-50k as it didn't do this. Hauling a trailer, up hill, 5-6 people in vehicle I want to know it shifted gears. Not harsh, just positive engagement, not slipping slow rev hang.
I contacted BG and explained what I was feeling. They confirmed everything I said is what the ATC+ is supposed to do, softer less harsh shifts etc. They sent me an email with the details. I went to head service manager with it. He read it, called advisor and mechanic in, confirmed my complaints and their responses with them with his door open. He walked out asked for my keys and said if I don't mind please stand in the shop and watch the mechanic pour the 14qts of new T-IV into machine and do the exchange again with no additives. Please come back next week and the week after and he will do that again. He apologized for the inconvenience and shut the door with advisor still in there. I never had an issue after that with any requests, TSB's etc. Same service advisor, probably hated me but was at least was pleasant and cooperative to me.