3rd gear whine?

[rebXehle420]

I was driving to work today and noticed a faint whining noise while accelerating in third gear.
Anyone know what this could be? Truck only has 700 km on it

It did not make this noise when I first got it.
I shifting pretty quick a couple times but I havent taken it above 2.5, 3k and havent gone WOT yet at all. Could rough shifting be the cause?

 

[autobodyX]

You need loader exhaust! A little gear whine in the higher gears is normal. I could hear it in my red truck, it was less noticeable with the REDLINE MT90 gear lube.

 

[Richard15]

Try changing the fluid to redline