I was looking at the latest order photos in Diesel Era the other day and noticed a little detail that differs from earlier SD70MACs. On the right side of the cab right in front of the step handrail there is a little 'hatch'(?) that looks like an MU connection or a toilet plug. I'm guessing it's for the toilet but i'm not positive. Anyway this isn't on any of the BNSF units that i'm aware of; don't know about the earlier CSX or Conrail units though.
I see what you mean about the MU looking object on the side of the cab. I think you may be correct in that it could have something to do with the toilet or drain... I doubt it would be an MU connection in that odd location. It could also be a plug location for a tester or diagnostic tool. I honestly don't know. If you have any back issues of Diesel Era, look at V11, #3 (May/June 2000 issue): at the bottom of page 49 is a picture of CR 788, which also appears to have this same "plug". Maybe someone else can enlighten us Chessie
It must be a Conrail thing; it's one little detail that CSX modelers will have to do on their SD70MACs... Whenever they get em! I didn't think it was an MU connection, i just couldn't describe it any other way~