[chuzz]

I'd try a fluid and filter change first. If you replace the transmission, the obvious choice would be the one with the least amount of miles on it.

 

[chuzz]

Mark C, do as Imperial Crown said. Get that Dexron out of there ASAP or you're going to have to replace the transmission. That crap will kill it in no time. I'd suggest you get a case of ATF+4 and just flush it. I wouldn't drop the pan and put in a new filter. You've already done that. Just remove the transmission return line and flush the old crap out. I'm not sure which line is the return on that car, but perhaps IC or someone else can tell you. Don't drive it anymore until you do this.

 

[chuzz]

You're welcome, dude. Keep an eye on it and see how it behaves. Odds are that since you put the wrong fluid in it and drove it, that there's still some Dexron mixed in with the ATF+4. Hopefully it won't be enough to cause any problems. I guess time will tell the tale.