What is this thing called, Luv?

[Abner Mality]

So, I've got this rattle coming from both rear wheels of my '80 300SD (116). It is very irritating, but I only notice it on the gravel road toward home; never on the highway. A friend told me it is probably something loose in the emergency brake.

I just came in from crawling underneath the old gal, and here is what I found. There is a steel rod, maybe 6-7" long, just inboard the rear rotors -- hard to see from my gravel driveway perch. It has a bushing at the top where it is attached to the whatchamacallit, but is broken off at the bottom where it attaches to the thingamajig. Same is true on both sides.

I need to know what this part is called, and what it does. Having said that, I am still not certain this is the source of my rattle. While those of you in the know ponder, I'm going to run a search on emergency brake.

TIA