First a little history. My dad bought this new in 1998.
It's a '99 v10 crewcab longbed 4x4, currently has 53k on the odometer.
He passed away in '12 and left me the truck.
Always been well taken care of, tranny service done by Ford ~30k.
Never done any hard towing, just boats/cars maybe a load of firewood.

In August I drove the truck from MN to SoCal, without any issues.

Last couple weeks on two separate occasions, from a dead stop it felt like it was shuddering on take off.
Today going up a slight hill it was stuck in 2nd, wouldn't upshift and when it did felt like slipped badly.
Later in the day worked fine

I checked the fluid and it's full, looks clean, no foul burnt smell, etc.

Any of these signs of something to worry drastically about?
Or possibly something easy-ish/inexpensive to deal with? (electronics?)

Thinking a fluid change cannot hurt, and inspect the pan for any debris.
Any opinions?

 

Does the OD OFF light work when you press the button? Has the light been flashing?

 

Yep, light works...no flashing.

 

There are three bolts with holes in the center of them that love to come loose causing a pressure lose internally there for slipping and possible no gear symptoms. The bolts are under your valve bodies in your tranny. Search around and you will find where people posted about this. I think it was called like the support bolts coming loose or something. I did this on my wife's excursion a while back. The oil was good, filter looked good, but sometimes you put it in gear and it wouldn't go. I unscrewed the bolts by hand, cleaned them up and put medium gel locktite on them. Seach around to find the torque spec. I can't find where I saved this info. I think it was on my work computer. Hope this helped.

 

They are the feed bolts.

 

Drained the fluid & converter Sunday.
Fluid looked okay, but a little dark IMHO.
Doesn't have that nasty burnt smell though.

Pan looked fairly clean, some aluminum material in there.
Magnets were pretty well covered.
I'd say normal amounts.

One mystery piece of something in 2 chunks.
Magnetic, kind of flattened/chewed up
Pretty small, I'll try to get a picture of it.

Installed a new filter, and cleaned the magnets/pan.
Haven't had a chance to go buy fluid/fill it back up yet.

 

Pic of mystery object found in pan...

 

Found the paperwork...last transmission service was @ 41514

Per invoice dated 06/17/05 Ford Dealership;
Drained trans., removed pan, changed filter, and drained the converter.
Refilled w/ 14 quarts MERC3

Cost was $189

I dunno, never seen fluid or a filter get that nasty in ~12k.
I've seen cleaner fluid after 50k changes.
That & the part# on the filter I removed does NOT match the part number listed on the invoice???
Invoice lists part# YC3Z-7A098-BA
Filter I removed part# YC3P-7G186-BB
Wondering if my dad didn't get a lazy tech who just drained and filled it?

 

They are pretty beat up, so I'm not certain, but I think that's a valve retainer from a valve body.

 

Recommendation?

 

Find where it came from. If it is a valve retainer then it came from one of the valve bodies.