GlobalSecurity describes the Song as China's first new-design conventional submarine and notes that the improved Type 039G replaced the stepped sail of the lead boat with a level-topped sail. The same source also says later boats added anechoic tiles to help reduce acoustic signature.
| Program milestone | Detail | Source |
|---|
| Lead design | First Chinese new-design conventional submarine | Song Class Type 039 |
| Type 039G change | Stepped conning tower deleted on the improved variant | Song Class Type 039 |
| Acoustic treatment | Anechoic tiles added on improved boats | Song Class Type 039 |