I'd start with the Bachmann because there are alot of differences between the Athearn DD40 and the prototype. A DD40 and a DDA40X are very different locomotives. The main thing being the DD40 was never built.
I'd replace unacceptable details with detail parts and see about repowering it.
Modeling the Centennials - Union Pacific's famous 6900's Railroad Model Craftsman, November 1994 page 77 ( "CARTER, BRIAN", "CARTER, CHARLES", DD35, DDA40X, DIESEL, EMD, KITBASH, UP, CONSTRUCTION, ENGINE, LOCOMOTIVE, RMC )
Nick Fotis wrote: