Does any one know if a pre ban PWA lower has mil spec or commercial dimensions for the receiver extension tube?
I had one during the ban years. It had a Mil-Spec sized buffer tube.
I have a mil spec LMT tube on it as I figured it was made for PWA by LMT so it musted be mil spec. Maybe flawed thining but it works.
Threads are the same 
This is an impossible to answer question as these were sold as stripped lowers.
My op may have been a little unclear.
Will a pre ban pwa lower accept a mil spec or commercial dimension receiver extension tube?
Based on most of the replies, I am leaning toward milspec.
Yes. The receivers are all threaded the same and can accept a mil-spec or a commercial extension. It’s the extensions threads (the peaks aren’t there) and outside diameter which differs from mil-spec.
Thanks fellas!