Howling In 4wd

[jrod332]

I have recently put in a new front differential and replaced the front u joints well i was at it. I did some searching and found that people with 05's and trucks around that year had noise while in 4wd. My question is, how much howling is acceptable. It seems to be loudest when I let off the gas and im slowing down. This is my first winter with this truck and using 4wd so I dont have anything to compare it to other than my 99 s10 that was quiet in 4wd. Also should I switch to synthetic ATF in the transfer case? That fluid needs to be changed.

[RyanbabZ71]

Is it only in 4wd? If its all the time it could be a wheel bearing

[jrod332]

Yeah only in 4wd.

[knipper_03]

Typically the howling I experience sounds like fairly loud road noise. I do notice the most when coasting and 4wd is activated. My 2000 silverado with manual shift sounded the same. It not loud enough where I feel I need to turn the radio up to counter act the noise if that helps gauge the sound.