reminded us all on how to modify the basic John Deere no-till drill, the most common drill in America.
"Never used a 5400, but a JD 750 is a great seeder if you keep it in good shape. If you get one, unless it's in unusually excellent shape, you'll want to:
1) Replace all the opening disks
2) Put in one of the seed boot kits to take out the slop when the mounting holes egg out. I like the one from Craft Air Services, because you can replace the boots and not have to redo it.
3) Replace all the seed boots. Use the JD bolts when you do it. An ordinary bolt has threads at the shear points and will break. (Been there, done that)
4) Put the closing arm kit from RK Products on to take out the side to side movement on the closing arms
5) Replace the JD firming wheels with the ones from Needham Ag
6) Put the Needham Ag firming strips on those new seed boots
7) Replace those idiotic JD cast iron closing wheels with Exapta's Thompson wheel (my first choice) or the Martin 20 pt crumblers (a close second for me) "
I've never used the Thompson wheel here but I have used the Martin since 1995 so it would be my choice for a closing wheel for planter or drill. I would also recommend replacing the gauge wheel tires with a CIH tire or even better, one of Phil Needham's. It really improves the air to soil mix in the seed slot.
"That renovation does cost a bit and is a knuckle-busting dirty job. But after doing it you'll get much more uniform stands which lets you cut your seeding rate and it pays for itself in a hurry. "
As other posters have mentioned, you want the dolly wheels too. This helps float and maneuver the drill behind the tractor and helps in transport.
The air seeder needs these plus more tank plumbing and linkage modification. Allen Dean in Bryan, Ohio and Robert Adamic in Michigan can tell you how to make those modifications. Both are regular in attendance at the National NoTillage Conference.