How much is it to replace the spindle nut that causes the popping noise whenever you change from reverse to foward in the s2k? I have heard this for about a month, and I'm sick of it. How much and how long/difficult is it to install?

 

You'll have to do a search but there is a faq about it.
-Basically you remove the nut, use compressed air to force grease into the bearing and replace the nut. Requires ~29mm socket and 190ft-lb torque wrench.

You may want to check Service Bulletin 02-063 since that seems to be the cause of my noises.