| 1 | Herbert Schneckloth & Son | Davenport, IA | | Jun 23 1955 |
| 2 | Lloyd Thompson | Spring Grove, MN | Mar 19 1958 | Jan 01 2000 |
| 3 | Lloyd Thompson & Everild Ellenz | Spring Grove, MN | Mar 19 1958 | Jan 01 2000 |
| 4 | Charles H. Loomis | Denver, IA | Feb 15 1961 | Jan 01 2000 |
| 5 | Herman A. Wedel & Bill Grange | Fairmont, MN | Jul 24 1961 | Jan 01 2000 |
| 6 | Ross Sparrow & Son | Zearing, IA | Dec 01 1965 | Jan 01 2000 |
| 7 | Everett Steege & Sons | Fredericksburg, IA | Jul 10 1966 | Jan 01 2000 |
| 8 | Herman A. Wedel & Bill Grange | Fairmont, MN | Oct 10 1969 | Jan 01 2000 |
| 9 | James W. Millard | Hastings, MN | May 10 1971 | Jan 01 2000 |
