There are plenty of how-to's on this procedure, so I'll leave the details at a minimum as I don't think I have much to add, but there are a couple things as well as some concern for my transmission.

For one - I didn't mess with a special/modified hex key. The cheap 8mm I bought did the trick (maybe it's stubbier than most?). I just stuck it in there and took a large box end wrench (I happened to have a 17mm handy) for leverage and it broke loose w/o a whole lot of trouble. It took a good amount of muscle, but nothing outrageous. Once it broke loose I had just enough room to get it out of the way and I could use my fingers the rest of the way.

Two of my new pan bolts had imperfections in the torx fittings and wouldn't accept the tool. No extras were included. I had to reuse a couple old ones.

The wiring sleeve was not as easy as I expected. The old sleeve was stuck tight. I had to get a hold of it with a big pair of needlenose and twist it to break it loose then it finally came out. Installation was easy enough.

My $7 (harbor freight) manual transfer pump is working great. It only takes 10, maybe 15 pumps to empty most of a quart. A little messy, but again, no big problem.
My old manual pump was more like a pump on a soap bottle and it took FOREVER.

Concerning this car specifically. The pan was original. It had an '03 stamp inside. Fluid I originally thought looked pretty good, but once it was in a container it appeared very dark. I bought the car just 3 weeks ago (91k miles) and soon after getting it home (100mi) I found the trans to be leaking. It would leave a ~12" stain over-night. Obviously I could not determine how long it had been leaking. I've been trying to pay close attention to the behavior of the trans (although my wife is the main driver) and it has acted normally. I knew I needed to get the trans serviced asap -- this is asap.
I assumed it was the sleeve that was leaking, but the sleeve was dry. Apparently it was the pan gasket - possibly over-tightened bolts.
So -- I expected it to be low on fluid (hopefully a qt or less). I measured what came from the drain plug and got only 2.5-2.75qt. I did not measure the add'l drainage from when I removed the pan, but if it was more than a qt. I'd be surprised. So in total I don't think I even got 4 qts out of it. I've been reading 6-7 is typical.

I'm close to finished with the refill process. I think I had it close the first time, but it got up to about 50C so I decided to let it cool off and do it again to make sure it's right. It's going to take around 5 qts.

 

Look to get between 6 & 7L of fluid back in the trans. Ensure vehicle is level and fluid dribbling out at 40 degrees C and cap her up..

 

Rick (joycesjag), Wayne (cjd777), and I were only able to drain 4.5 to 5 quarts out of my 2005 S-Type's ZF last November at Rick's house (we did just a drain-and-fill, no pan drop / sleeve change). We allowed the pan to drain for maybe 45 minutes. So we decided that we would do it again one year later just to ensure that most of the remaining ATF would be relatively fresh. We're doing it again this Tuesday morning at Rick's house. I'm again expecting 4.5 to 5 quarts to drain out. That will be good enough for my purposes. Then we'll fill it up one more time and hopefully never have to touch it again during the remaining time this car spends in my stable....

We used Mercon SP last time and will be doing so again on Tuesday....

 

A year after adding the Mercon SP, how is the transmission? Shifting okay? Any early morning, cold hesitation?

 

I know that was to Jon, but SP's what Ford/lincoln put in their ZF's. I think the ZF community has generally accepted that it's suitable in jags, bmw's etc.

My wife, who rarely notices anything about whatever she's driving - said it's behaving much better than it was before the change. That it was acting weird on stops and starts. But - that likely has as much to do with having the correct fluid level as having SP vs LG6.

 

The Mercon SP in my 2005 S-Type has performed equal to or better than the factory Lifeguard 6 does. No issues whatsoever. I believe it is a completely acceptable ATF in these ZF 6HP26 units at about one-third the cost of what you'll pay for Lifeguard 6 from the least-pricey sources online....