Do you have a 3 speed or 4 speed tranny?
Dexron III ATF is still available and cheap - I think - I bought a 5 gallon bucket (mfd by Miles) delivered from Jeffrey "Dr. Evil" Beelzebub's site for about $45 delivered. Basically dyed light mineral oil, later versions (Dexron 4,5,6) are backwards compatible, if I understand the wisdom of the elders imparted on this forum and many others.
Question is STILL, 3 speed (TH400) or 4 speed (4L80 or whatever)? I'm going to guess you've got a 3 speed. Mine was "updated" too in 2009, but the power pack was still 6.2LNA/TH400/218 as original.
For 3 speed, the "correct" filter is one that meets spec, and there're about two dozen manufacturers out there, you can find the things for anywhere from $7 to $30 and they're all basically the same piece of filter material with a stamped sheet metal cover/mount, many "kits" come with pan gasket too.
AC Delco TF231's are cheap enough.
For a gasket I sprang the few extra bucks for a Lube Locker Turbo 400/TH400 Transmission Gasket 'cause I really hate working with Permatex formagasket, silicone or many of the other sealants popular with mechanics and gear heads. I get a headache from the Permatex stuff, and silicone I always manage to get all over my fingers, gloves, arms, clothing. I was surprised how easily the Lube Locker went on, torqued up and several hundred hours later it's holding up well. Reusable too.
If you have a 4 speed: never mind.
