| 1 | CDX | Cloudex Oy | Callsign: Cloudex, | FIN | AVCODES |
| 2 | CDX | Cedar Executive | Callsign: Cedarex, | RL | AVCODES |
| 3 | CDX | General American Transportation Corp. | 1/1941-7/1954; eliminated 7/1955 | | NAKINA |
| 4 | CDX | General American Transportation Corp. | 1/52; eliminated 7/55 | | NRHS |
| 5 | CDX | GENERAL AMERICAN TRANSPORTATION CORP. | | | PWRC |
| 6 | CDXA | CROSS ROADS TRANSPORT | | | SCAC4 |
| 7 | CDXB | CROSS ROAD CENTERS TRANSPORTATION L | | | SCAC4 |
| 8 | CDXC | C & D TRANSPORTATION SERVICES INC | | | SCAC4 |
| 9 | CDXD | CDS TRANSPORT INC (BROKERAGE DIVISI | | | SCAC4 |
| 10 | CDXE | COMMODITY EXPRESS | | | SCAC3 |
| 11 | CDXE | CARDENAL EXPRESS S A DE C V | | | SCAC4 |
| 12 | CDXH | C D T TRANSPORT LLC | | | SCAC4 |
| 13 | CDXI | CUMMINS, D XPRESS INC | | | SCAC3 |
| 14 | CDXK | COLLARD TRANSPORT INC | | | SCAC4 |
| 15 | CDXL | CADE TRANSPORT LLC | | | SCAC4 |
| 16 | CDXN | CAL DESERT EXPRESS INC | | | SCAC3 |
| 17 | CDXQ | CROSSROADS TRANSPORTATION | | | SCAC4 |
| 18 | CDXR | C D X-PRESS INC | | | SCAC4 |
| 19 | CDXS | CRESCENT EXPRESS INC | | | SCAC3 |
| 20 | CDXS | C & D TRANSPORT SERVICES | | | SCAC4 |
| 21 | CDXU | CEREAL DOCKS SPA | | I | BIC |
| 22 | CDXV | CRISTIANI, DAN EXCAVATING CO INC | | | SCAC3 |
| 23 | CDXV | CRISTIANI, DAN EXCAVATING CO INC | | | SCAC4 |
