I've got a Yankee safelight that takes filters 4" in diameter I believe (not in front of me at the moment).
They are different than the circular Kodak filters which are 5".
I only have an amber and I need a dark red for ortho materials.
If such a thing exists, let me know, and if you've got one, even better.
ALTERNATIVELY, if you've got a red bulb that you want to sell, I'd take it.