If you need one of those bottom pieces do you have access to a milling machine, the bottom well looks like a job for an endmill and a ball flute cutter along the sides, take a woodruf type cutter to do the T shaped pocket. Mill out the sides and with a sharpie and a belt grinder go ahead and do the radiused sides, you should have a finished part in 1-2 hrs time I think.

As far as the comments about no one making them because they are for rivets. Just wondering what makes that part particularly a riveted part as opposed to bolt on? Did they do anything special to make those a rivet down mount that you wouldn't do if installing today with bolts?

I have access to manual and CNC milling machines at work. (And can run/program them.) I was hoping for an off-the-shelf solution before I sunk a bunch of time into a couple pipe anchors. I have a whole caboose to restore, and these anchors are only a small detail in the grand scheme of things. :)

These anchors could be bolted on. They were only riveted because that seems to be the fastener of choice when the caboose was built in 1941.

For those who are interested in this project: We've made some good progress this year. Exterior paint has been stripped off. We are gearing up for sheet metal replacement in the coming months. We hope to sandblast and paint this summer. Hard to believe she was sitting in a scrap yard a little over a year ago!