The earlier note about VXE-6's R5D sent me back to October 1990 at Chandler Memorial Airport in Arizona. In amongst the assembled Biegert Aviation DC-4/C-54 freighters was this example. The colours suggested an ex-Deep Freeze aircraft, but I could find no markings to readily identify it. However, the N44915 identity of ex-Bu56528 fits in nicely with the other machines present (N44904 - N44914), so I'm picking it's one and the same. Another minor mystery cleared up!