Does anyone know of a manufacturer, besides Armalite, making complete AR-10B upper receiver assemblies that are compatible with the early Armalite AR-10 rifles utilizing converted M-14/M1A mags? Armalite seems to be out of stock on there uppers at this time. Any help would be greatly appreciated! 
buy em separately
Noveske uppers are compatible, but they were discontinued.
Not sure if this is the part number you want…in stock though.
https://dsgarms.com/armek0130a
That’s an AR-15 upper receiver.
Yep, my bad.
Thought I was on their AR10 page.
I have a complete rifle AR10T-C. I just want to change upper receivers to a lighter weight bbl, etc.