My old 5x7 Durst used these incandescent bulbs.
I found this one in my bits & pieces stash.
It works.
I can't use it, but shipping it would cost as much as a new one,
... if you cold find one...
If you're willing to spend $10.95 for USPS flat rate shipping, it's yours.
Otherwise, I'll use it in my porch light 'till it burns out.