Anyone know where I can find this brass part?

Those are angled double step stirrups.  They are available in HO but of course not in O-scale.  Scale City Designs does make a metal angled stirrup which would be better than a melted lump.

http://scalecitydesigns.com/sc...ails/steps-stirrups/

Bob posted:

Those are angled double step stirrups.  They are available in HO but of course not in O-scale.

 

Precision Scale shows a listing for angled double step stirrups in O scale that is very close.  Check their freight car details catalog.

If you ever wanted to try your hand at scratch building now's the time. Do you have a soldering iron or gun ?  Stirrup steps are about as simple as it gets.  Materials ?  Have you ever seen heavy cardboard boxes with big copper looking staples.  They used to be copper now it's plated steel. Get yourself a handful and flatten them out.  You have your material.  For a double stirrup form the outside first then make the inside rung. Make yourself a pattern for bending the outside so you make them all the same size. then solder your inside rung on. If you let the sides of the outside extend up a 1/4" or so longer than needed you can solder a shim of copper at the very top roughly a 1/4" wide X the width of the stirrup at the top. Solder this on the outside face of the stirrup and you use this as a glue tab to epoxy on the inside of your car.          j

eBay is where I have gotten mine. Search "brass"; look at the "grab bag of parts/details" kind of listings. I have found all sorts of parts that way. Sometimes you have to take the wheat with the chaff, but some of those unwanted parts lead to other projects....and so on.

Of course, searching "brass steps" and/or "metal steps" wouldn't hurt either. Brass is just the most common metal for model RR details.