I just got one of those ancient ones back to life with LP from a NGas conversion. Grills like a beast now.
As Dave mentioned it's a pretty standard part (QCC regulator+hose) available anywhere. (Almost always terminates with a 3/8" flare fitting on the BBQ side)
Only thing to watch out is...
Did a restoration job on a Kijiji find of a Summit 450 bbq (4 burner front controls). But of course, the previous owner did the official propane to NatGas conversion (when it was actually offered by Weber back in the day).
Unit runs great now even though I swapped out the orifices for...