I remember a Sierra Pacific from WAY back that operated some Convairs out in the Mammoth area. I think they were owned by a ski resort or something.
More recently I have seen an old 737-300 with Sierra Pacific on the tail out in Salt Lake City and Newark. I think it was a "born again" charter outfit out of Tucson, last I saw their airplanes was early 2004, so not sure if they are still operating or not.