[Raleigh]

I'm no expert, but I think Philco potted the caps to keep any moisture from degrading the line filter caps. Since they were connected line to ground, they'd have more catastrophic effects if they shorted or leaked than most other caps in the chassis.

I use X/Y caps from Just Radios, which are disk-shaped. They fit fine, except they stick out the open bottom of the Bakelite box just a tiny bit, not enough to see or to interfere with the fit.

Most of us leave the Bakelite block in place after replacing the caps because it's a convenient place to connect AC and transformer lines to those filter caps, and to connect one or two things nearby to ground. You could do the same thing with a terminal strip, I suppose, but the Bakelite shell looks good.