Spacecrab,
That doodad is from, GROUP24-01 --HAND BRAKE, called
641921 Clip, retracting spring
As far as I can tell, it's only job is to give your spring an attachment point to the clevis/pin connection on the operating lever (AKA brake arm). I didn't have one (didn't have any hand brake parts back there) but using Lawrence Wade's pictures to help identify what was missing:
Notice the bend

I ordered one:
https://walcks4wd.com/search.asp?keyword=641921Below, I've attached images that will hopefully help. I honestly don't remember if the ordered part came with the bend or if I just added it to help with spring alignment.
On the clevis, in the same group above, it's listed as
GM-144242 Clevis, adjustable, 5/16"
in the clutch group, GROUP 11-02 -- CLUTCH CONTROL PARTS, that part is listed as
632177 Yoke, adjusting end, 5/16" (Clutch control lever)
The most obvious comparison I'd note is the shaft size (obviously can't be interchanged if threads are different!) but I'd have to crawl underneath to do a closer comparison as both are still attached right now. So, right now, I don't know if they're interchangeable.
On the rubbing, do you have the final clip (3 clips total) that secures the cable housing to the crossmember? On mine, the cable is very close to the rear support on the crossmember.