Hey,
I am the proud owner of a 97 Limited Supercharged 4runner. Its an auto. I bought it used in 02 (for 11,900!!!!!!) and it had the S/C on there already. I have recently noticed a slight vibration-ish noise happening only at very specific RPM's namely 2300-2500. It has been almost unnoticeable even to one of my professional friends, I only know its there cause its not what it used to be. I have a steering rack leak, from wheeling really hard but I doubt that has anything to do with it. If you have any suggestions on where to start looking, I would really appreciate it.

Universals on driveshaft maybe.

As speedracer said - try greasing all the fittings on the propellor shafts, including the splines and double cardan joints.

If it doesn't matter what gear it's in, maybe it's your nose drive on the S/C. They have to be repacked periodically.

http://www.gadgetonline.com/Supernose.htm

Thanks for the help guys! I lube my u joints n drive shafts everytime i change the oil, so I doubt its that. The sc nose assembly sounds like a good idea though. Ill chack it out

I just had the EXACT same problem with my '90 4runner, it happened to be the u joint at the rear diff needed to be replaced, hasn't done it since. good luck
Casey