Oh yeah, changing old fluids AFTER you have put the vehicle through some of the most stressful activities possible and a long drive down and back - good idea. I'm trying to figure out how that red dust gets in the sealed tranny and diffs? And we wouldn't want fresh grease in the bearings in case some dust got past the seals. And bearings with 30K worth of use and not being reset shouldn't ruin them...
Be sure to replace all fuses with wire so the dust won't cause them to short out!