I have a 99 Ram 1500 Van w/ Starcraft Conversion. There is a ridiculously loud whining noise when I accelerate. I had the wheel bearings checked and they seem fine. Could this noise be coming from the rear. I was underneath and saw evidence of a leak coming from the rear differential. It was only midway up the cover and looked to be coming from a flat circular plug. Could loss of fluid in the differential cause this noise? Also, is it something that can easily be remedied?

Also, I have lost power to the rear radio and headphone jacks. All the fuses I've checked are good. The T.V. and Video player are working fine. Any suggestions? Thanks.

 

If indeed the noise is coming from the diff, and it is low on fluid, it is unlikely that just adding more fluid is the fix. Most likely little pieces of metal have been circulating through the gears and bearings, and your looking at a total rebuild.
You can try popping off the rubber cap you noted, and see if the fluid level is flush with the cap and add some more.

So don't stress the headphone jacks for now. You've got real problems.