Happen to be at the junk yard at the right time over the weekend, saw a 08 Passat with deployed side airbags being dropped off and it had power seats. With the side airbags deployed, the seats were worthless, so I was able to get the lower track assembly at no cost. So, lets see what the lead screw really looks like. Sorry about the bad photos, had to use a cell phone.
Everything kind of bolts up together and such. Able to strip it down to separate left and right side guides.
There are a couple of jam nuts at one end.
Remove the outer jam nut, 12mm socket.
Now slide the upper section of the track forward.
The other end of the screw is welded to a bracket that is in turn riveted to the lower part of the seat track.
There is a another steel plate under this section, clamped on that in the vice and drilled out the ends of the rivets. Then punched them out. This only took a few minutes.
Once the rivets are removed, pull the lead screw assembly out the rear. In the middle is something like a gear box, and the other jam nut on the end. They just unscrew without much issue.
The lead screw is welded the the L bracket at one end. I used a cutting wheel on a grinder and made a slot as to free the lead screw.
That is that. A bare lead screw and one with other with the bracket still attached. The lead screw is about 12.25" long. You get 4 nice same nuts as well. They are dimpled so that they don't turn freely on the treads.
The width of it, 7.89mm
And I hope this is useful as well, the thread is .73mm wide.
I have no need for these, if anyone wants them, float me a crisp $5 bill and I'll mail them out.. or pick them up for free. Other wise I'll just toss them. I hope someone finds this info useful.