K Frame

You have something unusual. It might be a LATE 1972 V8 A body unit.
This is from the Schumacher site pictures.
A K 1.jpg

The one above is a 68-72 V8 A body K member according to the Schumacher site. Note the 3 holes in the middle of the flat section.

A K 2 (2).png

Yours have those same holes.
Now here is a B and E body K member. ONE hole:

B E K 1.jpg
A frontal view would help since the B and E K members that I have seen are curved across the front while the 67-76 A body units are flat.
Same goes with the lower control arms.
The A is flat across the front, the B and E are curved.

B body:

B LCA 2.jpg