Helpful diagrams from the Kadee site. A lot of information on this page.
Added 745 and 746 diagrams. 4/3/13
Kadee 806 short
Kadee 847 Underset shank. Coupler center and mounting height are the same.
Kadee 742 Overset shank Increases mounting height.
Kadee 745 Plastic #817 draft gear.
Kadee 746 Longer coupler shank noted.