| JACX | Johnstown America Corp. | added 7/92; 1/94-7/2000 |
| JAFX | J.A. LaFortune | Apr-38 |
| JAGX | J.A. Garfield | 10/57-10/66; eliminated 7/67 |
| JAIX | JAIX Leasing Co. | added 1/96; 7/2000 |
| JALX | Jos. A. Likely, Ltd. | 1/52; eliminated 10/53 |
| JAIX Leasing Co. | added 10/96; 7/2000 | |
| JANX | Jan, Inc. | added 4/89; eliminated 7/92; 1/94-7/2000 |
| JARX | John A. Roebling's Sons Co. | 4/38-1/52 |
| John A. Roebling's Sons Corp., subsidiary of the Colorado Fuel and Iron Corp. | 10/57; eliminated 7/58 | |
| JBBX | James B. Berry Sons' Co., Inc. | Apr-38 |
| JBCX | James B. Clow & Sons | 4/38-1/52 |
| JBIX | Jimbetco, Inc. | added 1/80; 1/80; eliminated 1/81 |
| Tank Car Services, Inc. | added 1/81; eliminated 1/86 | |
| JBPX | PacifiCorp Electric Operations & Idaho Power Co.-Jim Bridger Project | added 4/91; eliminated 7/92; 1/94-7/2000 |
| JBRX | Bakery Trading Co. | added 10/94; 7/2000 |
| JBSX | James B. Shatto Co., Inc. | added 1/58; eliminated 7/58 |
| Jay B.S. Corp. | added 7/58; eliminated 10/59 | |
| JCEX | John S. Carlson and Co., Inc. | added 4/81; eliminated 1/86 |
| JCIX | Jones Chemicals, Inc. | 7/65-1/80; eliminated 7/84 |
| JCLX | Jaffe Car Lines, Inc. | eliminated 7/79 |
| Mid-Am Equipment, Inc. | added 7/79; 1/80; eliminated 10/84; added 10/93; 1/94; eliminated 7/95; 7/2000 | |
| JCMX | James C. McCanless | added 4/78; 1/80; eliminated 4/88 |
| JCOX | Jordan Co. | 1/52-4/70; eliminated 4/71 |
| JCSX | Sawyer Slade Gas of Jacksonville, Inc. | added 10/74; eliminated 1/75 |
| Sawyer Gas of Jacksonville, Inc. | added 1/75; 1/75-1/80 | |
| Sawco, Inc. | eliminated 4/84 | |
| Sawyer Gas of Jacksonville, Inc. | added 4/84; 1/94; eliminated 7/97 | |
| Heritage Operating L.P. | added 7/97; 7/2000 | |
| JDAX | J. Dietrich & Co. | Apr-38 |
| JDIX | Jim Dobbes, Inc. | Jul-00 |
| JDMX | Joseph Transportation Co. | added 1/2001 |
| JDPX | Jacob Dold Packing Co. (Refrigerator Cars) | Apr-38 |
| JDSX | M&C Railcar Leasing, L.L.C. | added 1/97; 7/2000 |
| JE | Jerseyville & Eastern R.R. | 4/61-7/65 & 1/75-1/80 |
| Joppa & Eastern R.R. Co. | 1/94; added 10/96; eliminated 7/99; 7/2000; added 7/2001 | |
| JECX | Western Resources, Inc. | added 1/93; 1/94-7/2000 |
| JEFW | Jefferson Warrior R.R. Co., Inc. | 1/94-7/2000 |
| JEPX | PSI Energy, Inc. | added 1/99; 7/2000 |
| JETX | J.E. Thompson and Associates | 10/57-4/61 |
| JFDX | Jack F. Duckworth | added 1/72; 1/75; eliminated 4/75 |
| W.K. Horney | added 4/75; 1/80; eliminated 1/85 | |
| JFSX | John F. Stegner Co. (National Car Co.) | Apr-38 |
| JGRX | Graham Tank Line Co. | added 1/59; eliminated 1/60 |
| JGS | James Griffiths & Sons | 1/75-1/80 |
| JHCX | Julius Hyman & Co. | eliminated 4/55 |
| JHLX | J.H. Leftwich & Co., Inc. | 7/65-10/66; eliminated 10/68 |
| JHMX | Alabama Power Co. | added 4/98; eliminated 7/99; added 10/99; 7/2000 |
| JHPX | Huntsman Chemical Corp. | added 10/83; 1/94 |
| NOVA Chemicals (USA) Inc. | Jul-00 | |
| JHWX | John H. Witte & Sons | Apr-38 |
| JIMX | Reese Tank Line Co. | added 10/58; eliminated 10/59 |
| Custom Car Service Corp. | added 10/59 | |
| JJJX | JJ Rail Car Leasing Ltd. | added 1/95; 7/2000 |
| JJRD | J and J R.R., Inc. | added 4/86; eliminated 1/91; 1/94-7/2000 |
| JKBX | John Kenneth Burbridge | Jul-00 |
| JKL | J.K. Line, Inc. | 1/94-7/2000 |
| JKWI | Johnsonburg, Kane, Warren & Irvine R.R. Co. | added 10/82 |
| JLLX | LaRoche Industries, Inc. | added 1/97; eliminated 7/97; 7/2000 |
| JLMX | John. L. McCarthy | eliminated 1/90 |
| JLSX | Jones & Laughlin Steel Corp. | 4/38-10/66; eliminated 1/70 |
| JMBX | Jumbo Transportation Co. | added 4/62; 7/65-10/66; eliminated 1/69 |
| Falley Petroleum Co. | added 1/69; eliminated 4/69 | |
| Falley Corp. | added 4/69; eliminated 7/69 | |
| JMHX | J.M. Huber Corp. | 4/38-7/2000 |
| JNLX | J. Neils Lumber Co. | 4/38 & 10/57; eliminated 10/58 |
| JNSX | JNS Marketing Co., Coastline Rail Service Division | Jul-00 |
| JNTX | John Neas Tank Lines | added 4/80; eliminated 4/87 |
| John Neas Tank Lines, Inc. | added 4/87; eliminated 7/91 | |
| Enron Products Marketing Co. | added 7/91; eliminated 1/94 | |
| JORX | Johnson Oil Refining Co. | 4/38-1/52; eliminated 7/56 |
| Jormac, S.A. de C.V. | added 1/95; 7/2000 | |
| JOVX | JoVic Tank Line | added 1/62 |
| J&P | Joplin-Pittsburg R.R. | Apr-38 |
| JPCX | John Powell Chemical Co. | Jan-52 |
| JPRX | The Rausch Co., Inc. | Apr-38 |
| JPX | Jovita Perez | Jan-52 |
| JQGX | James Quinlan, Inc. | 7/65-1/80; eliminated 7/82 |
| JRCX | Jansen Rail Car, Inc. | added 7/90; 1/94; eliminated 7/96 |
| GLNX Corp. | added 10/96; 7/2000; eliminated 7/2000; added 10/2000; eliminated 4/2001 | |
| JRLX | J.R. Lawrence | 1/52-4/61 |
| JRSX | J.R. Simplot Co. | added 10/60; 4/61-4/70; eliminated 1/74; added 10/87; 1/94-7/2000 |
| J&SC | Johnstown & Stony Creek R.R. | Apr-38 |
| JSC | Johnstown and Stony Creek R.R. Co. | 1/75-1/80; eliminated 10/83 |
| JSIX | Jahncke Service, Inc. | added 1/65; 7/65-4/70; eliminated 1/74 |
| JSMX | Jewett & Sherman Co. | 4/38-7/65; eliminated 1/66 |
| JSRC | Jackson and Southern R.R. Co. | added 10/84; eliminated 1/95; eliminated 7/95; 7/2000 |
| JSRW | Ontario Eastern R.R. Corp. d/b/a Jersey Southern Ry. | added 4/85; eliminated 4/87 |
| JSSX | National Car Co. | Jan-52 |
| Fruit Growers Express Co. | 10/57-4/61 | |
| Jersey Shore Steel Co. | Jul-00 | |
| JSX | Jacob Stern & Sons, Inc. | 4/38-1/75; eliminated 4/76 |
| JSYX | J.S. Young Co. | 1/52-4/70; eliminated 4/73 |
| JTAX | Trinity Rail Management, Inc. | added 7/97; 7/2000 |
| JTBX | J.T. Baker Chemical Co., Taylor Chemical Division | 1/52-10/66; eliminated 4/69 |
| JTCO | Jacksonville Terminal Co. | 1/75-7/2000 |
| JTHX | Thomas D. Hicks | added 1/69; 4/70-1/80; eliminated 7/84 |
| Merchants Investment Co. | added 7/84; eliminated 1/89 | |
| Railmark | added 1/89 | |
| Citicorp Railmark, Inc. | 1/94; eliminated 7/96; 7/2000 | |
| JTIX | Joseph Transportation Inc. | added 4/2000; 7/2000 |
| JTJX | Joseph Transportation Inc. | added 4/2000; 7/2000 |
| JTLX | Joseph Leasing Ltd. | Jul-00 |
| JTMX | JTM Industries, Inc. | added 7/96 |
| ISG Resources, Inc. | Jul-00 | |
| JTPX | Joseph Transportation Inc. | added 4/2000; 7/2000 |
| JTSX | Joseph Transportation Inc. | added 4/2000; 7/2000 |
| JTTX | Trailer Train Co. (FMS flat cars specially modified or equipped by members of Trailer Train Co. with miscellaneous devices for special services | added 1/66; 10/66-10/68 |
| Trailer Train Co. | Apr-70 | |
| Trailer Train Co. (flat cars specially modified or equipped by participant railroads with miscellaneous devices for special services) | 1/75-1/80; eliminated 1/92 | |
| TTX Co. (flat cars specially modified or equipped by participant railroads with miscellaneous devices for special services) | added 1/92; 1/94 | |
| TTX Co. (flat cars specially modified or equipped by participant railroads with miscellaneous devices for special services, equipped with end of car cush.) | Jul-00 | |
| JVRR | Juniata Valley R.R. Co. | added 1/97; 7/2000 |
| JWAX | North American Car Corp. | 7/65-1/80 |
| General Electric Railcar Services Corp. | 1/94; eliminated 1/2000 | |
| General Electric Rail Services Corp. | added 1/2000; 7/2000 | |
| JWCX | The Celotex Corp. | added 4/68; 4/70-1/80; eliminated 7/81 |
| JWFX | J.W. Flammer Co., Inc. | added 4/68; 4/70-1/80; eliminated 4/89 |
| JWKX | J.W. Kerslake Co. | added 1/71; 1/75-1/80 |
| JWRX | Jim Walter Resources Inc. (captive service) | Jan-94 |
| Alabama Power Co. | added 10/94; eliminated 7/99; added 10/99; 7/2000 | |
| JWX | Jennison-Wright Corp. | 4/38-1/75 |
| JXPT | Jaxport Terminal Ry. Co. | added 1/90; 1/94; eliminated 10/97 |