What's the difference in these two fillers? They both fill end of stroke? Thanks!

Vac-- an internal piston engages the walls of the pen on the downstroke, producing a vacuum. The walls widen at the bottom, which exposes the vacuum to whatever is on the far side of the point-- ideally, ink.

TD-- A tube is sealed except at the top and bottom of its stroke. Drawing up creates a vaccum which is then equalized at the top of the stroke-- bad time to have the pen in the ink. Pressing down creates an overpressure, as the sealed tube is made much shorter, which crushes the internal sac. At the bottom of the stroke, pressure equalizes again, sac resumes its shape, and whatever is on the far side of the point is pulled inside.

The irony is that the one that takes longer to describe is WAY easier to maintain.

Cool, so the Vac Fil is sac less?

Yes - the Vac-fill is truly sacless. Sheaffer actually had a lot of talk track for their sales people to use against Parker, who claimed their Vacumatic pens were sacless (so what is that little rubber thing at the end - oh, a diaphragm, not a sack, right. . .).

Personally I love vac-fill Sheaffers. I would rate them as my favorite filling mechanism, though they are a bit more difficult to restore than the TD.

John

My absolute favorite pen to write with is a wartime vac. Actually, there's two of them tied in first, one fine point and one medium. Crazy smooth points, gobs of capacity. I like it notionally as a filling system but the TD wins for me because it's such an easy repair when you find one in the wild.

I'm sure I'd quite like the other seven vacs I've got too, if I could afford either the tools to fix 'em or the services of someone else who already does.

What pens came with the touchdown?

Have a look at PenHero.com's PenGallery. Apart from the initial TD lineup in 49-52, there's the "Dolphin" 500/800/1000, some Imperials, and... nuts, memory fails. Check out the site. It's hours of reading and a lifetime of learning.