Just going over my recently acquired 03 v6 tracker while changing the rear diff fluid I noticed the pinion was a little on the loose side. Not much but definitely loose. Oil didn't have metal flakes, I think it is salvageable. Going to try to retorque it and hope for the best, wish me luck.

I will torque it down until play is eliminated or until I get to 14 inch pounds whichever comes first. Yes, not proper, yes bandaid fix...

Well, the nut has loosened off!!
I didn't have a torque wrench that reads inch pounds that low, it wasn't very stiff either, but all I did was put it back to where it was, and go past 1/8".

I think the bearing should be replaced.

When I went out to the road, it sounded way more horrible for 8 miles. I made a rather brisk left and suddenly the noise went away. For 30 miles it was quiet as a mouse. I had it up to 88mph but didn't go back in time, it was quiet. Only towards the end of the 50mile trip did i notice some driveshaft vibration while decelerating.

I also replaced both diff and transfer case fluids. I wonder if it was a lock of lubrication noise?

Since we are on topic, I put it in 4x4, above 40 mph I get terrible driveshaft vibrations. I know the rear shaft ujoints are good, need to check the front. Can a bad transfer case mount do this? My last tracker had no problems going 75mph in snow in 4x4 but it wasn't a v6 either, it was a 93

I would replace the bearings, it that was loose your preload is probably way off.

I need the bearing replacement procedure, some of the old links like afks faq don't work for me

I will see if I can track down the preload setup. Luckily you can take out the third member and set it up outside the axle.