My car isn't charging while running, so I'm trying to check the fusible links. My haynes manual shows one black wire running to the starter solenoid, and then going to the fusible link on my '86 LG4 Trans Am. Now, when I go underneath the car, I can see 5 seperate wires, 3 of which have little rubber things with numbers stamped on them. One has 20 stamped on it, one has 15, and the other I can't read. I believe these are the fusible links, but which one do I check, and is there a way of checking one without actually cutting it out of the wire?

 

Try pulling on it. If it stretches then it's blown, if it's firm then it's most likely ok.
You could also poke a sharp point through the wire insulation (after the link) and use a test lamp or meter to verify the presence of power.
The first (and easiest) test you should do is to put a lamp on the B+ post on the alternator with the engine stationary. There should be power or else the link is blown. You should also get power on the brown wire when ignition is on. If not then check the C/H fuse.