| Official |
|---|
| 1.8 | If You Have to Know | 4:31 | Lonnie Mack | Strike Like Lightning | |
| 1.8 | If You Have to Know | 4:31 | Lonnie Mack | Strike Like Lightning | |
| 1.8 | If You Have to Know | 4:31 | Lonnie Mack | Strike Like Lightning | |
| 1.8 | If You Have to Know | 4:33 | Lonnie Mack | Strike Like Lightning | |
| 1.15 | If You Have to Know | 4:31 | Lonnie Mack & Stevie Ray Vaughan | The Alligator Records 25th Anniversary Collection | |
| 1.8 | If You Have to Know | 4:33 | Lonnie Mack & Stevie Ray Vaughan | Blues Story | |
| 1.8 | If You Have to Know | 4:33 | Lonnie Mack & Stevie Ray Vaughan | Blues Story n°1 : Les Rois du blues | |
| 2.5 | If You Have to Know (feat. Stevie Ray Vaughan) | 4:33 | Lonnie Mack | S.R.V. | |
| 1.11 | If You Have to Know | 4:33 | Lonnie Mack & Stevie Ray Vaughan | Blues Story n°1 : Les Rois du blues | |
| 2.5 | If You Have to Know | 4:33 | Lonnie Mack feat. Stevie Ray Vaughan | S.R.V. | |
| 1.8 | If You Have to Know | 4:33 | Lonnie Mack & Stevie Ray Vaughan | Blues Story | |
| 1.23 | If You Have to Know | 4:33 | Stevie Ray Vaughan & Lonnie Mack | SRV | |
