10/22 50th Modular Stock

[Blueduck]

Sure it's been asked, but apologies my search-fu not working for me tonight.

My dad just picked a up a 50th anniversary 10/22 model with the modular stock.

Is it available aftermarket? Absolutely loved it when I felt it, hope it was not just a one off for those guns, as I'd like to get couple for current 10/22's I already own.

Thanks!

 

[9x19]

I've bought two from the same seller over at RFC. I haven't seen them listed by Ruger.