Thanks everyone for all the help and comments! Also a big thank you to Jpetersjr for the pics of the fuel gauges and cab back wall. Those will help out a lot! Anyway, as far as building locomotives I plan on continuing with more U-Boats. I've pretty much built up a library of interchangeable parts, so its makes it fairly simple to build a U18B, then a U36B, with a few modifications. Anyway the next project in the works is the U36B and MATE. I'm also strongly considering a U23B, U30B/C, etc. As far as the other suggested Canadian locos, never say never, but they aren't very likely at the moment. Both examples look pretty distinct and would be single modeling projects, if that makes sense.
@Jpetersj - I've yet to start on the cab interior. Right now I have a low poly version for the exterior model.
@BNSF650 - you're correct, the front door is cracked open a bit. I'm going to do another variant with it closed.
I still need to familiarize myself with Blender a little more. Honestly I've had a lot easier time working between Maya and Gmax than Maya and Blender. Unfortunately Gmax isn't an option. Eyein12 volunteered to try to import the finished models into the game. Ultimately I would like to give it another shot myself but I haven't worked on that aspect since the blueprint editor is acting wonky. I still may have to take him up on the offer though. At first I was under the impression that I would have to animate the wheels, but upon further reading I realized that part is taken care of in the sim. So the only things I need to familiarize myself with in Blender, is the hierarchy system, smooth/soft edges, etc. I did have the Railworks shader set ups working in Blender but its been a while since I've messed with that and I've probably forgotten it all by now.
Here's a few grabs of the U36B and MATE. These include some of the high res details that I will bake into the normal and AO maps.