Could be one of a number of things, as it could be in any vehicle.
A dodge caravan may be experiencing rear brake noise due to needing new brake pads. This may also be due to worn rotors.
drive belts tensioner/under chassis
Transmission mount
The grinding noise in the front of a 1990 Dodge Caravan could be a cv joint. If it is, it probably only grinds when you take a sharp turn. There is one located on each side.
Bearing going bad?
The pump will need replaced if it is grinding.
If its a metal to metal sound its probably a wheel bearing
Bad tire? Rotate and see if thumping changes
we had rattleing noise on our passenger side van, it turned out we had to tighten the coil spring, and finally had to replace it
Loose belt - will sound like a screeching noise.
Starte could need a shim.
check your stabilizer links as well as your sway bar bushings. the sway bar bushings might look ok but what happens is the hole gets egg shapped causes clunkinking noise s going over bumps. just had the same problem in my shop. 2002 dodge caravan.