| Abbreviation | Definition |
|---|---|
| FGLK | Finger Lakes Railway Corporation |
| FGLX | Factor Gas Liquids |
| FGLX | Factor Gas Liquids Incorporated |
| FGMR | Fruit Growers Express |
| FGMR | Fruit Growers Express Company |
| FGTX | Florida Gas Terminals |
| FGW | First Great Western |
| FGWX | Federal Grain Inspection Service (USDA) |
| FGWX | Federal Grain Inspection Service (USDA) (Scale Test Cars) |
| FIBU | Flexitank |
| FILX | Fruit Industries Ltd (Wellman) |
| FILX | Wellman Incorporated |
| FIMX | Franklin Industrial Minerals |
| FINU | Finn Lines (Interpool) |
| FINU | Interpool Limited |
| FINX | Finley Co. (Trinity Rail Management) |
| FINX | Trinity Rail Management Incorporated |
| FIR | Flats Industrial Railroad |
| FIR | Flats Industrial Railroad Company |
| FISZ | Ecorail |