Interestingly, the JSQ continued to "record for" Epic all the way through 1966, while simultaneously recording for Columbia (again). Same company, but still, I wonder if the Epic deal was for recording more "popular composed.
For Columbia, in 1963, the recorded their epochal Bartok cycle. In spite of the fact that it's somewhat "legendary", it has yet to receive a CD release in America. However...French Sony Classical put this out in 2002:
https://www.discogs.com/sell/release/2422878
I monitored this item and one American seller popped up with a quite affordable set. So it does exist, and I did Carpe Diem all over it:
Could probably benefit from a modern remastering, and its a drag that #4 is split between two discs.
But these are THE 1963 performances, it IS on legit CD, and you CAN make it into 3 CDs of your own making AND have them all in sequence.
So overall, life is good, and Summer With The Juilliard String Quartet continues!