SP C-628 page: Yard Slug Rebuilding
Heavy Switcher Renumbering:
In mid 1973, the SP began a program to rebuild two C-628 and one C-630 unit as heavy yard slugs to work between pairs of SD38-2's at West Colton yard in southern California.
| Hump Slug number | 1965 number | original number |
| SP 1000 | SP 7121 | SP 4862 |
| SP 1001 | SP 7115 | SP 4856 |