I know that the attached nugget of news is not the central topic in this article, but it's sure the one that really jumped out at me, considering how NS was a long, lone holdout in finally adopting AC traction at all. This is the first I have heard of any road seriously entertaining converting existing DC-traction units over to AC.
Quote from news article on Progressive Railroading web site:
In the meantime, the department is considering the next potential outgrowth of the rebuild effort: converting motors from DC-traction to AC-traction on a portion of NS' 1,200 Dash 9s. Proposals from three companies on three continents are under analysis, and GE is one of the proposers, says Graab. "The conversion would make the units more reliable and we would gain tractive effort," he says.
Full article titled Norfolk Southern Railway to roll out modified GE locomotive model as part of multi-year rebuild program can be found at the following address:
http://www.progressiverailroading.com/norfolk_southern/article/Norfolk-Southern-Railway-to-roll-out-modified-GE-locomotive-model-as-part-of-multiyear-rebuild-program--40373