In 1966, EMD started production of switchers with 1,000 or 1,500 hp which were powered by the new 645-series prime mover, compared to the 567-series of the SW900 and SW1200. The SW1000 had a V8 and was built 119 times between 1966 and 1972. 43 of these went to the Burlington Northern. The SW1500 was powered by a V12 and could be distinguished from the SW1000 by its two exhaust stacks. By 1974, 808 SW1500 had been built, of which 204 went to Southern Pacific.

The SW1001 was an improved variant of the SW1000 that had used the frames and the more rounded cab roof from the SW1200. 230 had been built by 1986. While only very few of the two original variants were exported, the SW1001 found customers in several countries. The RENFE class 310 built under license in Spain was a variant of the SW1001. The SW1504 was a variant of the SW1500 of which 60 were built for the Nacionales de México in 1973.