HO Alternator install
 

I plan on upgrading my stock alternator in my 04 blazer to a high output one. I've been shopping around on sites such as sonic electronix but how do I know what will fit? As far as system power, I dont know what I'm gonna be running. I just want a hefty alternator. Any help would be much appreciated.

The AD244 case alternators will fit. I would highly recommend either DC Power Inc. or Singer alternators for an HO alt. The 250A Singer in my Jimmy does a fantastic job and is the closest thing I would consider to a budget option. The DC Power XP series 250A in my van is the best HO alt I've seen. Voltage on it is so rock solid with every accessory running, the headlights on and the Sundown SAZ-2000 running full tilt. That alt is a beast.

When it comes to high output alternators you really can't and don't want to cheap out. The "upgrades" they do to cheap alternators often make them worse than keeping your stock one. Output at idle is comprised to make high output at unrealistic engine RPM's or worse they can't even do that when they get hot. The high output Alta built by reputable companies will do the majority of their capable output at engine idle and can do at least the rated output when hot above idle.

If you're not going to be doing thousands of watts of power and a ton of current draw you could probably grab a stock AD244 alternator from a full size truck/suv and get plenty of output for most things. There are whole how to's out on the internet that tell you what vehicles to look in, part numbers and the like to do the upgrade really cheap. The only thing you have to change is the belt. If you do go with an aftermarket HO alt then you should also make sure to do the BIG 3 so the wiring can handle the increased output.