| 1 | A | B | C | D | E | F |
| --- | --- | --- | --- | --- | --- | --- |
| 2 | NBR 224 and 420 Classes - Summary |  |  |  |  |  |
| 3 | Original number | Class | Built | Rebuilt | Renumbered (year) | Withdrawn |
| 4 | 224 | 224 | 1871 | 1885, 1887, 1897 | 1192 (1913) | 1919 |
| 5 | 264 | 224 | 1871 | 1893 | 1198 (1913) | 1917 |
| 6 | 420 | 420 | 1873 | 1887 | 1241 (1914) | 1915 |
| 7 | 421 | 420 | 1873 | 1887 | 1242 (1914) | 1918 |
| 8 | 422 | 420 | 1873 | 1890 | 1243 (1914) | 1918 |
| 9 | 423 | 420 | 1873 | 1890 | 1244 (1914) | 1914 |

Question: What years were the 420/421 and 422/423 locomotives rebuilt?
Answer: In the NBR 224 and 420 Classes, the nos. 420/421 were rebuilt in 1887 and nos. 422/423 in 1890.