Hi folks..... newbie RV'er, first post. Just took possession of a 1999 Coachman Miranda that has just over 21,000 miles on it. It's in really good condition as far as I can tell. The only issue is that it's been sitting for over year without moving. I've put on only 100 miles since purchasing. The only thing I'm noticing is a slight ominous sound, vibration, coming from the rear of the vehicle only around 40-45 mph. Kind of sounds like a drive-line issue of some sort. Differential is full and no signs of leaking. After a 15 mile ride at 50 mph, the differential is quite warm to the touch. I can't leave my hand on it for more than 6-8 seconds. I'm going to pull out my laser digital thermometer and start monitoring differential temps. My question is what is the normal differential temp of a vehicle of this sort? Thanks in advance! I have a 1,500 mile trip back to Pennsylvania in the morning.