Rear Sight 77 50

[Black Fly]

Some previous owner of my faithful 77 50 decided to remove the blade and pin of the rear sight. Do I need to get a 77 50 specific rear sight, or was that sight used on other rifles. I'm guessing I'll need a complete sight or might there be a source of the couple pieces I need.
Thanks
Bfly

 

[Jimbo357mag]

Have you called Ruger? They might still have some sight parts.