On the true "750" drill, the first original closing wheels arrangement was a long 5/8" diameter bolt through a tube welded on the arm, through some spacers then through 2 sealed ball bearings in the cast iron wheel with a flat sheet metal grease cap covering the outer end of the bolt/nut. (Version "1")

This original arrangement did not hold up well in dirt so in the early 90's JD added a triple lip seal running on a steel sleeve on the inner side of the wheel. This second arrangement had a tapped RH or LH female thread in the tube welded to the arm. Used the same two sealed bearings and a special blue grease on the seal lips at assembly since there was no way to regrease them. (Version "2")

On the 1560 version, Deere switched to tapered roller bearings at the top of the closing wheel arm with a long shaft down to the cast closing wheel with NO bearings in the wheel (Version "3")

The reason I mention this is that it seems difficult/very expensive to change version 1 or 2 to veresion 3 as suggested in your original post. It seems like you would actually need to change everything including the closing wheel arm on back to the ground including the wheel itself. I would check out which version you have and what parts you are buying before placing an order.

If you have version 1 you can change to version 2 at some cost. Downside is you still have ball bearings. This application really should be tapered roller bearings, in my opinion.

Hope this helps understand the situation. Please correct me if I am wrong anywhere. There are a LOT of these drills out there.

Jim at Dawn