Someone likely added the flat piece under the pedal.  How is it attached?  Picture of the bottom of the pedal?

Actually, that was me. It's just held in place by carpet tape; makes it a little more stable. Upon further examination, the pedal footboard has a weld at the narrow part near the heel hinge. It appears that it's the heel plate from a swivomatic 395(?) welded to the forward part of a 396. Not sure about the model numbers, but one type has the Rogers logo in the casting, and the other doesn't, just the 4 slots.

The strap cam is machined out of aluminum, and is definitely not stock, as it has a different profile and functions more like a circular cam.

 I'm told that the pedal belonged to David Garibaldi. Whether it did or not, it has great action and feel.

Here are some more pictures I forgot to add in the last post.

This looks like a stock early 80's Swivomatic, but with some wing screws replacing the original drum key screws for faster adjustment. A picture of it can be found in the 1983,  8 page flyer on Drumarchive.com