One evening after I had picked up a Bowser PRR F30A flatcar kit I decided to cut out the missing holes in the cast underframe. This was a process of drilling a bunch of holes, then cutting and filing until they were the right oval shape. It's hard to tell, but I even filed out the holes in the crossbearers.
It's not precise, and I think I did two too many holes in the small sections where the trucks will be. On the track, of course, the underframe is largely unseen, but the very bottom of the holes can be seen when looking from the side on the layout.
It will take a little more work to finish the model, but this was a good project to just grab and do something on a night where I otherwise might not have done any modeling.
The Sunshine kit has the correct underframe, of course, but they are hard to find and the Bowser kit is not only easy to find, but inexpensive. And it's a pretty accurate model as is, with a few modifications.
More to come!