| GFV-29-03 | Retrofit versus conversion (definitions) | |
| GFV-29-04 | Proposed structure for a new regulation on heavy-duty engine conversions | |
| GFV-29-02 | Working draft of the proposed new regulation on heavy-duty dual-fuel retrofit systems | |
| GFV-29-10 | Draft minutes of the 29th GFV informal working group session | |
| GFV-29-09 | HDDF Retrofit: Outstanding issues | |
| GFV-29-03 | Retrofit versus conversion (definitions) |