The most common problem with a Bosch alternator in the '98-'02 Dodge Turbo Diesel truck is that the brushes wear out. Without brush-to-armature contact there is no electrical charge.
Some truck owners replace the Bosch alternator. Budget conscious owners rebuild the alternator with new brushes and bearings prior to complete failure.
GOULD Alternator Rebuild Kit (BOSCH) - DODGE ('98-'02)