SD45?

Hello. Does anyone know if the old Spectrum N SD45 has the same shell as the new improved version. I want to have a powered/dummy set but I don’t want to tear up a perfectly good new SD45 to do it. If I can find an old crappy, beat-up Spectrum on ebay or something from the first run, that would suit me just fine. Naturally my powered loco will be the new improved version…matter of fact, how does that old Spectrum SD45 run compared to the new version? Is it similiar or is the old version just a piece of junk, not even in the same ballpark with the new one?

Thanks,

MLG4’8.5"