Nissan really dropped the ball designing their brake rotors on the 4x4 Hardbodies. If you pop your front wheel off and take a look, you'll see right away what I'm talking about. Not only are the rotors bolted onto the truck, but they're bolted on BEHIND the hub assembly. Changing them out can be a real pain, but doing so saves you a lot of $$ (since most mechanics charge by the hour!). Here's some detailed instructions on what to do and what you'll need if you want to tackle the project yourself.

Step 1) What you'll need:
metric socket set, up to 20mm. (*note*-it HAS to be a thin wall set, as there's no space for impact sockets)
Metric Allen (hex) wrench set. (manual hubs take a 6mm hex, I'm not sure about auto hubs)
Gear Puller
Breaker Bar
Lots of WD40 penetrating oil
phillips #2 screwdriver
lock ring pliers
propane torch (plumber's torch)
wheel bearing grease
lots of paper towels/shop rags

step 2) the day before you start working, give all the bolts a good shot of WD40, as well as where the rotor contacts the hub. Jack the front end of your truck up and SUPPORT IT WITH JACK STANDS! You're going to be doing a lot of muscling on some of these bolts, and you don't want to have the truck come down on you. take the wheels off, but DON'T remove the calipers yet.

Step 3) have someone step on the brakes so you can loosen up the hub bolts and the bolts securing the rotor to the hub. The rotor bolts are going to be tight, so you may have to heat them first. The hub bolts take a 6mm hex key (at least the manual ones do) and the rotor bolts take a 14mm socket and may require a breaker bar. Careful not to round over the heads!!

step 4) take your entire caliper assembly off the truck. ignore the two 14mm bolts you'd use to change the pads, on the back side of the caliper there are two large bolts; remove these (they take an 18mm socket). If you don't want to disconnect the brake line, the assembly fits well on top of your front shock mount, and it's out of the way.

step 5) loosen the hub bolts the rest of the way using the 6mm hex key/allen wrench, but leave them in the hub (I just found it easier to keep track of them). pull the hub cover off (don't worry, nothing spring loaded is going to shoot out at you) and set it out of the way, where you won't be stepping on it or getting dirt/rust in it. Remove the hub/rotor bolts and put them where you won't lose them.

step 6) go clean your hands. seriously, do you want all that dirt and rust scale in your hub assembly?

Step 7) you're looking at the hub assembly itself, and there will be a locking ring 1/4 inch in from the end on the smallest diameter gear. use the lock ring pliers to remove it and set it aside on a clean rag. *note*-from here on it's best to put everything in a line in the order you took it out, just to minimize the chance of an 'oops' later.

step 8) grasp the largest gear set and pull. it should slide off around the axle shaft. set it aside with the lock ring. you'll be looking at what is basically a big steel washer with screw holes drilled in it and two phillips screws.

Step 9) using the #2 phillips screwdriver, remove the two screws and set them aside. If your fingers are small enough, you can slide the washer out of its cavity. if they're not, use a pair of slotted screwdrivers or something.

step 10) this next washer is threaded onto the axle. I used a pair of large needle-nosed pliers to unscrew it by inserting the tips into the large, unthreaded holes and pushing counterclockwise. once you remove this washer you'll be looking into a hole at your wheel bearings.

step 11) using the gear puller, pull the rotor/hub unit off the truck. your axle has a dimple in the end for this purpose, and the pull arm tabs fit well behind the part your rotor bolts thread through. pull the assembly until it releases its grip, then do the rest of the job SLOWLY by hand, making sure to catch your wheel bearing when it comes loose.

step 12) Separate the rotor from the hub assembly. Since I live in the salt/rust belt, I had to use a bench vise to clamp onto my rotor, and hammer a punch into the space between the hub and the rotor to get them apart. use whatever works for you.

step 13) take a break, you probably need it at this point. (I know I did)

step 14) reassemble the new rotor and the hub assembly. it's easier to do before you put them back on the truck. be sure to use lock-tite on the bolts! put the assembly back onto your axle.

step 15) repack your bearings with the grease. this part is easy, but messy. just smear some grease in the palm of your hand and work the bearings through it until they're well-loaded.
re-insert the bearing onto the axle. it'll take a good push, and maybe a few light taps with a punch.

step 16) reinstall the threaded washer, the unthreaded washer, the two phillips screws, and the hub gears. It's possible that during all this you've bumped the axle shaft, in which case you'll have to grab the CV boot and push it towards the hub in order to get the lock ring back on. reinstall the hub cover and its bolts (using lock-tite on them).

Step 17) Change the calipers, if you're going to, and reinstall them. change the pads, put your wheels back on, and you're good to go. it's a good idea after you've driven a few miles to check the bolts to make sure they're still tight.

Best of luck!