It is a 1/4 roll pin that goes all the way through. The center of this hole is 2"
from mating surface. It hold the quick release mechinism on the blade. The blade shaft is 1 and 1/4 " O.D. the quick release is 1.6" O.D.
The quick release button is 3/4" the hole for it is 6" center from mating surface
If you start off asking for help, you probably should not even start off.