Ok, I went and looked at the PC versionon myfriend's Guardian. I don't see difference except the arm is about 1" shorter. Here are some measurements:

PC version:
1. The mounting holes from front edge of first hole to front edge of second hole is about 5/8".
2. About 5/8" front-to-front on the holes where the hook goes as well.
3. The arm is 1" shorter than the original version (3.75").

That's the only difference. On my friend's Guardian, the cable slide slides about 1" back when draw. I hope this helps you. I haven't finish setting mine up yet, but one of my friend had one on his Equalizer (the original version). He said that he is shooting fine. He had it install on the second hole (which is the middle hole).