Not many.
And its MR rate remains very low, well below the C-17.
Speak with the lifters, speak with the aircrew, speak with AQP, A-5 and A-8 staffers (the guys that flew the jets and now work requirements and funding ), and they will tell you, time to retire the C-5’s.
And how many C-5’s will have the glass cockpit?
All of them. All C-5Bs and the two C-5Cs have already gone through the Aviation Modernization Program (AMP.) The C-5As are now in work. The Air Force plans to retire 22 C-5As next year, so those won't be modernized, but the remaining As will have the same AMP kit installed.
What the As won't get is the RERP that the Bs will get. No new engines and other reliability tweaks.
I understand that the C-5A/B has had a horrible mission ready rate for it's entire life. Hopefully these two programs will change that.