It's not that difficult, no real specialty tools required just a little labor.
Basically start with the front wheels and work your way down through the drive axles. You will want a prybar and an 1/2" impact if possible to make life easy. Once you get that all remove you need to pull the transmission, unbolt the mounts, you will need to support the engine. Remove the transmission, then it's time to remove the clutch and flywheel to get down to the rear main housing. I would suggest putting threadlocker on the flywheel (or flexplate) bolts when they go back on. Reassemble everything with the correct torque specs as alot of these smaller bolts on the clutch and flywheel have a tendency to snap if not torqued properly and that is a VERY big safety hazard.
Feel free to ask more questions if needed. I'm just giving you a broad idea of what you are getting into.
Some things you might also want to replace and/or check while you are there.
- Clutch Job (pilot bushing, TO bearing, etc.)- Flywheel (aftermarket)- Clutch Line (
www.splparts.com has a stainless one for the Altimas)- Drain and Refill clutch line fluid (helps to refresh the pedal feel)- Check Master and Slave for leaks- Axle CV Boots (repair / replace / inspect)- Axle Seals- Trans fluid (suggest Redline GL4 fluid)