Push Rod Tubes / Progressive Refinements
| Date Introduced | Chassis No. | Unit No. | Modification |
|---|---|---|---|
| 1946 | 054 617 | Corrugated tube ends fitted in a number of cases formerly with spring[1] | |
| Aug. 1949 | Several hundred engines with corrugated tube ends [2] | ||
| Dec. 1949 | 1-0 136 157 | 168 075 | Only corrugated tubes with cylindrical ends at both sides [3] |