I asked about 8.3 in August, since IBM had just sent me tapes for CMOD 7.1 and CMOD 7.1 PTFs
IBM's reply was that the 8.3 version is a multi-platform version designation, but has no changes for z/OS, and in fact it is the same thing. I guess they needed a new version number after 4 years or so.
Larry Wagner
City of Los Angeles