This in a 01 Durango, 360 magnum, and 46RE.
High miles on body, engine replacement and trans overhaul about 63k ago. Trans has been flawless, last fluid and filter swap about 10k ago.
Flawless that is until this past week.
Last Saturday I had to pull the dash out to replace the evaporator.
I disconnected the wiring to the steering column, and was gonna pull it (as recommended by Mitchell manuals) but instead I unbolted the seat and slid it back, so I could set the steering wheel on the floor pan as there was one wiring plug I couldn't get to,
I didn't pull the dash completely out, but set it back on the passenger seat which gave me enough room to access the heater box. I did have the battery disconnected from Saturday til Wednesday when I reconnected it and ran it long enough in the driveway to recharge the AC. My wife noticed that the speedo was buried at the high end (120) even though we never left the driveway.
I got it back together and other than the speedo being pegged, the "airbag" light was on, which had never been before.

Well I discovered that I didn't get the airbag plug snapped all the way back in. Did so, air bag light disappeared. Disconnected the battery again, plugged back in, speedo needle back where it belongs. We drove to the store in it Thursday. Stopped for gas, and when we pulled out (blame it on Zilla, we got gas at Love's, his favorite meet up spot haha) it shuttered like Hell, taking off in 1st. It has never done this before. Ever. Trans has been in there over 60k since rebuild. We had to stop for a light, shuddered worse there. All the way thru 1st for sure and I think into 2nd. Once it hits 3rd and 4th it's fine. But I have to wonder if I'm gonna make it fast enough to get into 3rd, it slips and shudders so bad getting there. Fluid is as red as off the shelf ATF. And full. Or it was Thursday when I checked it, I have driven it a couple of times close to the house with scanner plugged in among the country roads.... I haven't checked fluid since those last couple drives in the country. I've MAYBE put 25-30 miles on it since pulling the dash and reinstalling it.
What in the HELL does pulling the dash out, have to do with the trans flaking out like this?
The only weird stuff I noticed when driving with scanner (no codes either) was that governor pressure should pretty much follow MPH, there is a "desired" and an "actual" governor pressure that should both follow pretty much with MPH. Sometimes it will flicker to "desired" being double MPH, and then back to what it should be, sometimes it will "stick" at gov pressure desired =2x MPH" and briefly flicker at being close to desired reading showing closer to expected.
I do have a fresh, spare identical trans sitting under the bench that I got years ago at a "too good to pass up" price, only difference in my spare is it came from an R/T model which mine isn't. Same year, same engine as mine. (Don't thing "R/T" makes a bit of difference in this case)
Anyone ever hear of such problem that didn't exist before that showed up immediately after pulling a dash and reinstalling?

a WAG (Wild Ass Guess):

You found one loose wiring connection, there maybe another one or two.
I would go over all the electrical connections again. Also check the fuses.
Look real close at any of the wires / wire bundles that would have been placed
in a strained condition when you laid the steering column down. The connector
may still be plugged in properly, but possibly a wire got pulled from a socket.
Good Luck!

_________________
Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

Take it back to the shop that did the work. Tell them the trans worked fine before the dash was pulled. They need to fix it under warranty. You will not pay any more.

_________________
Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Thinking about when it acts up vs when it doesn't, I'm thinking it has to be mechanical within, especially when I saw all the glitter I did when I pulled my pan drain plug. So it's out and the one from under the shelf unit is on the trans jack ready to go in as soon as I find a parts store who has the right front pump seal in stock....
I did drive it 8-10 miles after I got the dash back together and it seemed fine then, before it went screwy. The way it's acting I'm almost thinking the overrunning clutch may have croaked. I didn't replace that when I freshened it up 60-some thousand miles ago. Who knows that may be original, with 311k on it for all I know.
I don't know at this point if the glitter in the ATF is cause or effect of whatever is causing this thing to act as it is .

No progress, haven't even looked at it in a while.
It's the wife's daily and she broke her wrist in 3spots so won't be driving for a bit.
And I've been going crazy with everything else besides .

People wonder why I gotta just about be dead before I go to a Dr..... Nother story.

Sounds like bad gas.
Will