Transmission Fluid Change?

I had a trans flush at ~120k and am glad I did. At 350k I'd probably drop the pan and have a look see first and change the filter. Then maybe have a flush. If you're having issues, usually it's too late from what I've seen. You can also do a full fluid drain and fill using a bucket etc. Google for the method.
For a dipstick, I'd make one using AN fittings long before I'd pay $200 for a custom car/racing one.

Change the fluid then change it again.

For what it is worth I had my '05 "flushed" at 165k. Not sure of the exact procedure they did tho. Then at 262k lost the fourth gear (OD) and had it rebuilt. Maybe I should have had it replaced at regular intervals (like 100k), who knows. Now has almost 300k on it.

Ok, to update my situation. And to hopefully help others. I finally had the time to get back to the exhaust shop and have the drivers side catalytic converter replaced. Instant success! I will do a little write up separately to explain my troubles.

In regards to cak's post earlier in the month. Overdrive usually is the first to go, unless the vehicle is dogged, then it can be any gear. The reason is the load on a 1 to 1 gear ratio, and usually a too small of drum and band, or clutch pack. Lincoln had that problem with the AOD tranny. The drum that the band gripped around was too small for the horsepower. An upgrade was the next biggest drum/band on rebuild. As always, clean fluid prolongs the inevitable.

Sent from my N9131 using Tapatalk

There is another thread on the CC but I had one go out around 80K then the other over 200K. Shop I went to (best in DFW - all dealers refer you to them) said expect about 80K from one. I'd recommend replacing them around 100K as on the Expy you have either 2 or I've even heard 4. This shop only charges 200 to replace. In my instance it cleared up other engine issues I had and a small price to pay to stay out of trouble especially if you plan on keeping the ride. Mine is now at 292K miles. It's all related.......

6R80 is ridiculous for a reman you are looking at $5,000 plus. If mine ever went I’d go a rebuild which can run half that.

Update #1:

Appreciate all of the information, opinions, and suggestions. As of now, I will not be dropping the pan, changing the oil, or replacing the filter. The reasoning is that I don't want to trigger something which ends up ruining the transmission. I'll just let it be until the inevitable and go from there.

As for plugs/coil packs, I replaced the coil packs - no improvement. Since I didn't want to risk myself breaking the SP515 plugs, I took the new SP546 plugs to a local shop and they should have them replaced this Monday. I took it in this morning, but they couldn't get the plugs off initially, so they're soaking the plugs over the weekend. Will give another update in a couple days.

Also, I forgot to mention this in the initial post: I had the catalytic converters replaced a while ago and the mechanic made a poor connection from the new converter to the manifold, which has resulted over time into pretty loud and smelly exhaust leak - sounds like a go-kart. Is there a possibility that this exhaust leak is also causing the engine shuttering, etc. symptoms?

When I changed the fluid in my Explorer (I was installing a new cooler anyway) I also installed an external transmission filter. Uses a full sized spin on filter to filter the fluid as it comes out of the auxiliary cooler. With that many miles on a transmission, and all the fears of loose transmission "gunk" clogging the internal filter I just rested easier with the extra filter. Havent had a problem with it yet.

Sent from my LML413DL using Tapatalk