Went for a 2 hour roundtrip with the van yesterday to pick up some parts for my jeep projects. Everything worked as usual when i left home, heres a list of everything that failed by the time i came home:
*Lights couldnt be turned of.
*Ac belt fell of
*Power steering belt fell of
*Diesel leaking from bottom of fuel filter
*Engine missfire
*And the most important one, insanely loud grinding noise from what i suspect is the auto transmission!

All the first ones are quick fixers and doesnt worry me, but obviously the noise is something more serious. It goes away as long as i accelerate or pull uphill. Its sounds terrible just keeping a steady speed on long flat stretches, and goes over to more like a slow rattling when coasting downhill. Hard to describe such a noise, but it could be described as trying to force a manual into reverse when doing 50mph... I could also feel the rattling and grinding with my feet on the floor. When idling the noise remains the same no matter what gear i select.

Any idea what might be the problem?

I have a spare e4od that i planned to rebuild and beef up during winter, now it looks like i have to speed up those plans. Whats the cheapest and simplest way to build a sturdy transmission? stuff that it would be stupid not to fix before i swap it in?

Could the noise possibly come from the engine??