I hear you on the tow vehicle. I remember spewing dif oil in my K series blazer every time I towed a heavy load.
*chuckles* Thats due to the crummy 12 bolt axle, man. Ya need a 14 bolt in there
Legends axles run rather cool for a race car axle. Mainly, due to the spool in the back. Without all the spider gears churning the gear oil, the heat buildup is cut in half!
Put in a good, expensive, full syn. gear oil and dont worry about it all season. Over a full season, you realy only put a few hours on all the driveline components. Gear oil wont even begin to brake down for 1000's of miles.