snip
BTW, those 4 bolts are loaded in shear, not compression.
Love It! A Structural engineer I am obviously not, in retrospect , what I was trying to get across, perhaps I should have written;
Note: The 4 bolts when tightened compress that unit to the frame, marrying them together making it "one",...
in lieu of;
"Note 4 bolts in compression that marry the unit to the frame making it "one", ..."
FWIW I knew what I meant!