I am looking to drain and refill the trans oil and wondering if ATF type 3 or synthetic ones such as Amsoil ATF would be sufficient for TH200R4. Also if Wix trans filter would be excellent replacement for AC Delco filter
You can take this for what it's worth, but I have used ATF Type "F" in everything except the new computer controlled transmissions for over forty years. I even used it in the T-400, full manual, reverse pattern trans in my bracket race car, and the T-350 in the Cutlass in my avatar. It doesn't have the "slipping" agent that Dexron has to make your trans slide into gear. An old tranny rebuilder told me to do that many years ago and it definitely works.
The Wix filter will be fine. I have used just about every fluid possible. I have used Type F, Tractor Hydraulic fluid, Dexron 3, conventional and synthetic, currently running half and half. I have also ran Dexron 6, part and full synthetic without ill effects, even mixed with Dexron 3.