Now you can see lightening holes onthe small offsetting plate

You can see from this view (pillow block removed) three lightening holes (.312" diameter) located between the two pillow block .250" mounting holes on the 3/4" wide offset spacer.
There is a recess on the contact area of the pillow block that is .375" wide, so the .312" lightening holes fall in this recess area.

Y13-11-27