I completed some routine maintenance today. I changed the lube in my RDU and PTU and did a drain/fill on the transmission. My MKS has 60,000 miles and the RDU had never been changed. The fluid that I removed looked very good - no surprises at all. I had changed the PTU lube and did the transmission drain/fill about 10,000 miles ago and the fluids removed from both looked very good this time as well. I ran about 30 quarter mile passes last summer and I am very pleased with the way these components seem to be holding up.
Before I go back to the track in May, I will put in a 160 degree thermostat and change the engine oil & filter. Should be good to go again!