Here's another series of shots as I go about fixing up the MILW RD "shorty fuel tank induced" frame.
(ABOVE) An overhead view of the frame... the super glued brass angle is the "keeper of the frame." I was hoping that perhaps the strength of the gap-filling ACC might be enough to keep the tight-fit between the left 2/3's of the frame (B end) butted up against the right 1/3 (A end), but I knew better from other work with cutting Athearn frames in the past making MILW RD SD40-2's.
As you can see, there was just enough open space between the frame and the fuel tank to allow wiggle room, and I knew that would not hold up in a time span of the model. On those earlier SD40-2's, I took care of this by gluing in the frames to the bodies - remember that those were non-powered efforts. Not the case with the Mt Rushmore engine!
So, out came some brass stock, and the drills and taps, and tiny screws. Ever find that as you get older, those 1/8" to 1/4" screws are a real bitch to get started into holes where you have limited finger room?
And, to make sure that things stayed fairly level and in line, I went ahead and drilled and tapped a 2-56 thru the brass angle form and into the frame bottom, As well as into the fuel tank end. There was just enough room left on the frame bottom to allow this and not get into clearance problems with the flywheel housing. 
Side view of the "new frame." For some reason, the top of stock Athearn frame for the "A" (front) end of the SD40-2 is a bit higher than the rear portion as it approaches the fuel tank area. This is matched up in the fuel tank area, near the depressed portions of the "A" frame that holds the flywheel. I had to mill down this "reinforcement" brass strip, not for "matching up," but for clearance with the body shell.Oh, and yes, I had to grind / fill out lots of the inside of the body shell down at the walkways to make this all fit in, including the small screw heads sticking out. If I had put the crews on the inside, I was afraid that there might be too close or no clearance between the screw heads and the flywheels.
The shell is fitting to my satisfaction on the frame, and when the body-mounted coupler boxes are screwed in, the whole thing is fitting darned good. Therefore, the next step is BODY WORK.
