1999 RD Alternator fuse

[Sidney]

Does anyone know where the alternator fuse is located or 1999 RD 688.

[Geoff Weeks]

Alternator output is not generally fused, as the voltage spike of dumping the load can damage anything still connected. I have seen fuseable links used between the battery and alternator, but not between it and the rest of the electrical system.

  I don't know about the truck in question exactly, but I would tend to doubt more than a fuseable link. Is the 12 volts present at the output stud with the engine off?

What are the problems? 

[Sidney]

Not charging. Rebuilt old alternator was charging at the post but not charging on the battery. Randy jumper wire from alternator to battery and it overcharged. bought new alternator it's still not charging have not tested it yet have not checked for 12 volts at post with truck off

[Geoff Weeks]

The fact that it charges when connected is a good clue, how did you connect? to which terminal? I think you are going to need someone who knows the wiring on that model, but I would trace the output wire back to where it connects to the battery (often at the starter motor) and look for a fuseable link in the wire. It will likely be in the first  few inches at the starter end (battery supply end) if it has one.