60 amp fuses

I have a 91XJ. 4.0 HO There are two 60 amp fuses in the box on the passenger side under the hood. They are marked ALT PWR 1 and ALT PWR 2 on the lid. What are they? What are they linked to? Thanks in advance.

Those are the fuses that isolate your alternator in the event of a "surge" from the thing. Replace with standard MAXI60 fuses.

If you upgrade your alternator past the 120A mark, you'll need to run a replacement output lead and install a higher-capacity fuse. I find that ANL fuses work well for this, and can be had in ratings up to 600A (which you certainly won't need - I usually keep them on hand up to 200A, which covers right up to Mean Green output levels.)

from what thing>?

Sorry - "thing" = alternator (referential pronoun, going back to earlier in the sentence.)

I got your PM, and answered you in more detail there. Hope it helps!