[Lynn Eades]

The centers vertically are 2 1/2"(63.4), and horizontally are 2 3/4"(69.8).
On mine the bump stop side is 12mm to the edge of the plate from the outside edge of the hole. The other side is slightly less at 11mm.
Suggestion; If you are welding them up. Pop your rivets out, put one or two holes in correctly (squaring the bkt to the hull and checking with the holes in your hull) and use the hull as a jig for the others.
Check the hole centers in the hook arm, to make sure it works with these measurements.