I have one of the RS shells. Dimensions are an issue. The shell is approximately 50% too large. It is a scale 15' wide. In comparison, the MTL GP35 is a scale 12', a typical boxcar is a scale 10' wide. A Full Throttle 2-bay hopper can actually fit between the fuel tanks on the shell. I have pushed back on Searails and hope they will address the dimension issue. The shell does look good and does capture the feel of the locomotive, but there are some real design concerns that need address such as trucks, couplers, etc. Again, Searails has my comments and I hope they will make adjustments before releasing these.
Rob