A-Line makes great metal sill steps which are bullet-proof when installed. Proof is that I used them exclusively on the resin boxcars I built some time back and they've never even thought of breaking. In fact, during my build I often forgot and rested the entire car on just the steps. No problem.
I needed to install the #29000 type (seen in the pic above) on the 1-1/2 door boxcar I built and needed to figure out what size drill to use to drill the mounting holes and how far apart to drill such holes.
Since I figured it out, you don't have to. So put this in your toolbox - or even better put a little note in with the steps wherever you store them:
Drill two mounting holes per stirrup step using a #75 (.021") drill (I confess I later reamed out these holes with a #74 - .225" - bit to make installation easier)
Drill the holes .064" apart (as you see in the pic above)
Place a drop of gap-filling ACC in a cap and dip the stirrups steps into it before inserting them in the holes. Alternatively, you could either rely on a press fit or just apply thin ACC after inserting them.
If you have any feedback on this tip - or additional tips of your own, please let us know in the comments!