That's odd. I can't find any replacement models for Millenium Falcon or Bear Gold, but there's this https://grabcad.com/library/lego-power-digger-1/
. It might work, but I can't tell if it's a complete model or if you download all the individual parts and then have to assemble it. If that's so don't waste your time on it.
Why weren't the models downloadable? I thought they were free to download.