Can anyone recommend a bolt-in replacement for the 5" speaker for this cabinet?

Thanks,
Justin

Just following up on this, in case anyone is curious. I ended up buying a Beyma 6B30/P 6" speaker, and the holes match up nicely with the mounting hardware for the original 6" speaker. (The 5" I wrote above was incorrect.) I did have to drill the holes slightly larger, but no big deal.

I can't compare to the original speaker since it was destroyed, but it sounds pretty good to me. Even though this isn't original cabinet for the NC-183d I'll be using it with, I actually like the look a bit better. It's the same height as the radio and they look nice side-by-side. Not that I could afford the original speaker cabinet anyway....