How do I identify what alternator I have in a '04 Yukon Denali

[Doubeleive]

the same thing applies to many things
say you have a laptop and it came with a 180w charger
and you plug in a 90w charger it will work (or should) but it will take longer to charge and that charger is going to get really hot because it is being worked 100+ % of what it was designed for.
and if you plugged in a 240w charger it is going to still charge the same time or very close to what it did with the 180w only now the charger is under less strain and won't get very warm.
electrical devices are normally designed to only "draw" a specific amperage, to a certain degree, if you plugged in a 600w charger to that same laptop it's going to overload and melt the inverter and likely start burning.

 

[Fless]

I figured it out.
There is a serial number and a stamp that says 145amp on it on the alternator
So its a bosche delphi 145 amp alternator

The OE 145A alternator has a black "spacer" between the case halves; the 105A one does not have the spacer. Glad you found the numbers on it.

 

[rockola1971]

*do not ever increase the fusible link
why? because the fusible link is built to prevent everything behind it from burning up, increase the link and you risk destroying modules, wiring, as well as a risk of fire.
upgrading the charge cable is standard

i should add that simply increasing the alternator amperage does not increase how many amps the vehicle will use, the extra amps just makes it a lighter load on the alternator.
any external/aftermarket equipment requiring more power should be wired separately with it's own wire and fuse's, relays, etc i.e. amps, high power lighting, cb, ham, etc

Yes. A fuse/circuit breaker in a car, home, factory, spacecraft is there protect THE WIRING. The fuse/circuit breaker is sized to the wiring. The wiring is sized for the load(s) which is anything connected to the wiring that consumes power. If a vehicle came factory with a 145a alternator and you stick a 160a or even bigger in, it will be able to charge the battery up faster than the original 145a alternator because the 160a+ puts out more current (power). Remember power is equal to volts x amps and since the voltage will be the same on the output BUT the higher output current of the "bigger alternator" raises a number up in that power equation which the current.

As an example:
145a alternator at nominal 13.8v = 2001w
160a = 2208w
200a = 2760w

The bigger output alternators need more stator coils so to do be able to house those the rear case halve of the alternator has to be moved further back from the front case halve and spacers are added in between. Some fancy really high output alternators physically are bigger and/or thick front to back and may even require a custom mount for installation.