| Abbreviation | Definition |
|---|---|
| IIRZ | III Transportation |
| IITU | Intermodal Tank Transport |
| IIZ | Issaquah Industry |
| IKCU | Interpool |
| IKKU | ICCU Containers |
| IKKU | ICCU Containers Incorporated |
| IKSU | TAL International |
| IKSU | Transamerica Leasing Incorporated |
| ILDX | General Electric Company - Lighting Business Group |
| ILDX | General Electric Lighting Business Group |
| ILIU | Tank Containers |
| ILMU | Flow Line Transport |
| ILPZ | Illinois Power Company |
| ILRV | Inland Lakes Railway |
| ILSX | Independent Locomotive Service |
| ILTU | International Liquid Transport |
| ILTU | International Liquid Transport Company Bv |
| ILUU | Institute Of International Container Lessors |
| ILW | Illinois Western Railroad |
| ILW | Illinois Western Railroad Company |