The GP40's have been there since the late October update. I know this because I ordered two MKT GP40's and received them the next day.
They are great, especially if you want to run a slightly different time frame. Just pop the MKT shells onto other GP38/40 mech's (with newer schemes, but still on black trucks/fueltank) I have and voila! 1985.
I also got some SD60/M's that I use on a single 60 chassis as pool power. I can run KCS, DRGW, BN, SOO, CR, NS, BN-patch....all with one mech and decoder.