Well, since I had to go through the ordeal of replacing my alternator, I figured I would help out anyone else who needed to do this in the future. Most common reason for an alternator failure on a Nissan truck? Muddy water crossings. Gets gunk up in the bearings, leading to a slow, noisy death.
As with all write-ups, i take no responsibility for what you do to your truck. I am not a certified technician, so take my advice/tips at your own risk.
Additionally, use all proper precautions when working on your vehicle. Wear gloves and eye protection at all times to prevent accidents.
Without further ado, here we go: Alternator Replacement - 2005+ VQ40DE
Disconnect the negative terminal from the battery. Remember to write down your radio presets.
Remove the 2 bolts holding down the engine cover and pop it up and out of the way. Loosen the clamps on both ends of your intake tube. Remove the 2 bolts holding it down and maneuver the intake tube out of the way.
Use a 3/8" socket wrench or breaker bar on the spring tensioner to remove the serpentine belt from the alternator.
Chock you rear tires and jack up the front-passenger side wheel. Set a jack stand and remove the pressure from the jack. Remove the front-passenger tire. Remove about 6 screws and 4 plastic retainers from the inner fender and remove the inner fender cover. This will give you all the access you need to get to the alternator.
The alternator is pretty much right behind the fender liner.
There is 1 long bolt and 1 short bolt holding the alternator in place. Start by removing the short bolt, which in on the lower side attached by a metal bracket to the alternator. Loosen the bolt on the other end of the bracket so it swings down a little and out of the way. Loosen the upper long bolt on the alternator, but don't remove it completely just yet.
Behind the coil bucket, locate the electrical connections for the alternator. There is one plastic clip with the main wires and a ground bolt. Remove both of these connections.
While you're back there, remove the retaining clips/zip ties that are holding a large bundle of wires to the back of the alternator. Do not try to pry the clips from the alternator. Instead, the zip ties can be undone (reusable zip ties) so you can remove the retainer itself later. Slip the wire bundle out of the way.
At this point, you may want to look at the front of the alternator to make sure there are no wires/hoses in the way of removal. Finagle anything out of the way and get back to that upper long bolt.
Remove the upper long bolt and maneuver the alternator out of the engine bay.
This is what a filthy alternator with shot bearings looks like:
As compared to this shiny new (rebuilt) one:
Here's what your engine compartment should look like at this point. Nice and empty.
Install is reverse of removal. Remove the zip-tie clips from the back of the old alternator and reinstall them on the new one. Finagle it back into the engine bay and line up the bolt holes for the long upper bolt. Connect the lower bolt through the bracket. Connect the ground and main power harness to the alternator. Torque down the bolts to factory specs.
Check out this awesomely quiet, clean alternator:
Reinstall the serpentine belt, intake tube and engine cover. Re-connect the negative terminal of the battery. Start 'er up. Enjoy the noiseless engine for a minute or two before you shut it back down.
Put the fender liner back in and button it up. Put the wheel back on and torque the lugs to factory specs. Jack up the truck to remove the jack stand.
Clean up your tools and tend to your bloody knuckles and arms while enjoying your handiwork.
Hope this write-up helps someone muster the courage to save a few bucks and tackle this project themselves. It really wasn't all too bad, took me and a friend about an hour and a half from start to finish with regular hand tools, and I wanted to pass along the knowledge.