From PS3 Development Wiki
NOTE: Patch version does not include entire firmware, not suitable for clean installs without prior FW
- System changes
- System stability during use of PS3 format software and network services has been improved.
- System security has been improved.
 PUP Hashes
3.73 RETAIL/CEX-PATCH | MD5::7fafd0908c35995ebf001419a1bf78f1 | SHA1::c9fa36d7d5f74c3fe3a7fd898eb4bceeb1526b31 | CRC32::7195356b | CRC16:: | HMAC_SHA1::