Only for the record, I do have separate CDs for the respective versions, as specified below [as I haven't secured any license for Fortran, etc., I'm only listing my C/C++ compiler. However, maintenance releases always contained overlays for each of the MIPSPro 7.4 compiler products]:
MIPSPro C Compiler 7.4: 11/02 [812-0707-004]
MIPSPro C++ Compiler 7:4: 11/02 [812-0400-010]
MIPSPro 7.4.1m: I can't find that CD right now or maybe I'd missed it at all - don't remember which anymore...
MIPSPro 7.4.2m: 03/04 [812-0980-005]
MIPSPro 7.4.3m: 11/04 [812-0980-006]
MIPSPro 7.4.4m: 11/05 [812-0980-007]
Additionally, there was also a separate CD
Compiler Execution Environment 7.4: 11/02 [812-0924-002]
All of the above require IRIX 6.5 or later.