Header rubbing on center link and idler arm

Yeah, that weld looks pretty "factory". Never hurts to clean it up and reweld it while it's apart, though.
Shims are just 1/4" plate with a hole in the middle, nothing special. You can probably buy pre-made ones somewhere, but why? I'm sure you can find something else to spend that money on!
Edit: I type slooow. I see Rusty's got ya covered.