I've been holding on to this tidbit of information for about two months now, but I was told that the MTA would be buying 200 Ex-Toronto Transit Commission 2003-04 Orion VII Gen-II Diesels. These units are Detroit Diesel Series 50EGR Powered with Allison B400R Transmissions
This article by TimeOut confirms that: https://www.timeout.com/newyork/blog/the-mta-just-bought-200-diesel-busses-to-use-during-the-l-train-shutdown-043017
A couple of my connects from Toronto had told me that officials from the MTA was up there to look at the fleet a while back and hold told me that this purchase was forthcoming, at the time I had no idea why the MTA would be 200 used Diesel buses when we were buying a frig-ton of new buses, but this makes sense as keeping our older buses would not be as reliable as these units that are newer and that have received a rotisserie-all around rebuild in 2013-2014.