As a box code, 1684 is used for 10 post office box locations.
Suburbs using 1684 as street code
| Suburb | Town | Province |
|---|---|---|
| Carlswald | Halfway House | Gauteng |
| Kyalami | Halfway House | Gauteng |
| Kyalami AH Ext 1 | Halfway House | Gauteng |
| Kyalami Estates | Halfway House | Gauteng |
| Kyalami Ext 2 | Halfway House | Gauteng |
| Kyalami Hills | Halfway House | Gauteng |
| Kyalami Hills Ext 3 | Halfway House | Gauteng |
| Kyalami Hills Ext 5 | Halfway House | Gauteng |
| Kyalami Hills Ext 9 | Halfway House | Gauteng |
| Willaway | Halfway House | Gauteng |
| Witpoort | Halfway House | Gauteng |
| Kyalami Business Park | Midrand | Gauteng |
| Sunvalley | Midrand | Gauteng |
PO Boxes using 1684
| Suburb | Town | Province |
|---|---|---|
| Crowthorne | Halfway House | Gauteng |
| Kyalami | Halfway House | Gauteng |
| Kyalami Estates | Halfway House | Gauteng |
| Kyalami Ext 2 | Halfway House | Gauteng |
| Kyalami Hills | Halfway House | Gauteng |
| Kyalami Hills Ext 3 | Halfway House | Gauteng |
| Kyalami Hills Ext 5 | Halfway House | Gauteng |
| Kyalami Hills Ext 9 | Halfway House | Gauteng |
| Barbeque Downs | Midrand | Gauteng |
| Barbeque Downs Ext 56 | Midrand | Gauteng |