So I have been plodding along building this kit from long ago that’s no longer made. It’s a fun project! I’m at the point where I need to add brake gear. The instruction sheet shows a chain for one end , going to a brake wheel. I’ve never seen that! Does anyone have any familiarity with this set up? Thanks in advance!
The mechanism makes sense, but a full-chain seems unusual. Normally it's just a rod with a segment of chain at the top for the brake wheel housing. You may need to reference some historical photos, but I would venture to guess that this is not prototypical. I've built a few Ye Olde kits that had some dimensional or scaling issues, so I wouldn't necessarily trust their models as the most accurate.
It looks as though they are doing a bit of freelancing. Just sticking a brake wheel into the end of the car. Also, the bottom illustration much differently indicates a vertical staff- which seems to me as being more appropriate. For parts, perhaps take a look at the San Juan Models (former Grandt Line) site. They have quite a selection of brake details.