As for that o-ring seal . . . a simple auto supply o-ring will work short-term, generally, but NOT long term.
After I'd been in the dealership parts deal for a year or so, I was at the tech's window one day. A tech came up looking for an o-ring for a THM350 dipstick tube. He'd put one on about 2 weeks earlier and the car was back for the same situation. He mentioned that one of my associates had just gotten a correct-size o-ting from the generic o-ring selection. I figured that GM had a number on that item, so I looked it up. Sure enough, there was a part number AND we had some. I gave him one and "end of problem, long-term". So he started asking for THAT one.
I suspect that Chrysler is the same, only thing mightr be finding one at a dealership might be problematic, unless the one for a current model vehicle might be the same size. Otherwise, go to a reputable trans shop and see if they have one.
Key thing is that a generic o-ring doesn't appear to be compatible with ATF as such, whereas the OEMs will be. In this case, specificity is necessary.
Be sure to catch any run-off from when the tube is removed, or might it be a good time for a fluid change anyway?
CBODY67