Power Trac PT1845, John Deere 2240, John Deere 950, John Deere 755, Jacobsen Turf Cat II
<font color="red"> any other sites have extensive blades? </font>
Don't know of any. I bought some high lift hardened blades from a Gravely dealer for my 1845, but I was shopping for blades to cut in half, so paid no attention to the center hole. That dealer had a whole wall of blades of different flavors, not just for Gravelys, but for a lot of other mowers, as well.
Have you looked on Lawnsite ?