Yesterday I felt like just getting underneath my truck to do just a little visual inspection (very bored) and I noticed my drive shaft looked a little odd (see picture). There is no noise out of the ordinary and does not shift any different. Basically, cant tell if something is wrong or will be shortly. I was just unsure if the drive shaft is allowed play or not so that's why I started this. The shiny area is about 3/8-1/2". Thanks for the help!

Truck is:

04 FX4
106,000 miles
HBS 2.5" Level

 

That is the area were the input shaft moves in and out of the transmission as the truck flexes over bumps-perfectly normal, it looks like the seal is doing it's job.

 

X2... Everything looks fine. When the suspension goes up and down, that is where the driveshaft adjusts.

 

yea its normal....but with 106,000 those non servicable u-joints are gonna be pushing their limits......im in the same boat with 105,000

 

I have 190,000km on mine and I'll probably have to replace the driveshaft real soon.

 

All good.