RE: Alt fusible link (140 amps) blowing, HELP!
Well, I can give ya some ideas as to what to look for. First off, keep the battery disconnected.
Also I have to ask, at any time, did you smell sulphur (rotten egg type smell) at any time? If so, this would normally indicate either one or more bad cells in the battery, OR, your voltage regualtor may have malfunctioned to the point where excessive voltage is in the system, although nothing has really failed yet.
If the rotten egg smell is present, don't do any testing where sparks could occur. For that smell to be present, battery acid has boiled, which expedites breakdown of the plates due to excessive heat. Just remove the battery if the smell is present...lol
The next thing I would do is unscrew the fusebox from wherever it mounts. My truck happens to be on the fender skirt right behind drivers side battery. The fuse box should have 2 large diameter wires. Probably a 6 or 4 gauge. One goes to the negative cable, one to the pos cable. After you get the fusebox undone, try to look on the underside of it. Mine was hard to flip with all the wires attached. Try to guestimate where and which wire(s) are for the fuse that keeps blowing. If there's a short under the fuse box, there HAS to be some damage. See if something something is shorting to ground. If it all looks good, I would suspect the alternator/regulator. I don't believe there's anything on the truck other than a direct short, OR a continuous increase in voltage that could blow a fuse that big.
When you start the truck, ever notice how everything "goes out" while you hold the key in the start position? That's an intentional disconnect to prevent "spiking". It gives the battery all available starting power power, which cause a voltage drop during cranking. If electrical appliances such as headlights, radios, etc are left on, damage could result from that low voltage.
Get the alt tested. Any autoparts store will do it for free.