I can't tell if the slot is the same or not, this one was made to mount into a flat panel and yours looks like it meets the grille cloth but who knows.
There is a picture of your set on the ETF Site:
http://www.earlytelevision.org/rca8tr26.html and it looks the same as what I have.
No way you could reproduce this thing, it is a big chunk of molded plastic, reverse painted, sort of a prism actually. you are welcome to have this one.
Here's a photo, note the "scratches" are actually dirt on my scanner
