EXTREMELY bad vibration in the front! pls help

[N8USCG]

so it started to snow and ice over here in Kodiak Alaska. so i put the truck in 4wd for the first time in a while. for about a week all was well, then i started to get this grumble coming out of the drivers side front axle. the grumble got worse and worse until it was literally shaking the entire truck and commanded my attention. i did some research online and by process of what i thought was elimination determined that i had a bad hub on the drivers side. so i ordered a set a warn premium hubs, installed them as per the instructions and had high hopes of the problems being fixed. hopped in the truck put it in 4 wheel drive and nothing has changed, it still has the same vibration.

i took it to my base where i could work out of the snow and jacked up the front of the truck so i can check the front end. unlocked the hubs and spun, no binding. locked the hubs but not in 4 wheel drive, no binding and the same goes for hubs locked and in 4 wheel dive. NOTHING. so my conclusion is that it only happens when there is weight on the front.....

i need your help i have no idea what it could be. here are my symptoms...hubs unlocked in 2wd on the road no sound or vibration. hubs locked in 2wd has a faint grumble, that sounds like i have a tire rub. but i have nothing rubbing. hubs locked in 4wd has the horrible vibration! like before almost sounds like a squeaky tire rub but nothing is rubbing and i am going straight down the road. now hubs unlocked but in 4wd there is no vibration. also this vibration seems like its dependent on vehicle speed, as in it starts off as a thud thud thud and increases as vehicle speed increases

i am thinking it is the axle CV joints but i am unsure and i don't think i can fix it my self with the tools i have. but i am wondering if anyone has any input or experience with this and can lead me in the right direction. please help i know there are some pretty knowledgeable people on here.

thanks,
N8

[N8USCG]

Bump....thinking a bad u joint or axle seal? any ideas??

[HarvestingInternationally]

i would go with ur theroy that its bad cv joint..any play?

[N8USCG]

i tried to determine if it did and it seemed tight, however i was in a rush so im gonna bring it back to the base and take some time and look for the cause. im just looking for a direction to head in, since it seems like no one has had this exact problem.
THANKS

[HarvestingInternationally]

is there fluid in the diff? enough fluid? correct type of fluid? im not sure if the front diff requires a friction modifier..also did u check the ball joints?

[F250SixOH]

U joint would seem like a good place to start since it only happens with the hubs locked.

[N8USCG]

IH you know i need to check it. does the FX4 come with a LS diff in the front? i know it does on the rear of most models and my truck has one. and Six Oh ya thats kinda where im at right now. but i am gonna bring it to the base tomorrow so i can check it out again.
i really appreciate it guys!

[MikeThompson]

N8, Just wanted to let you know there's a military member forum on here. PM a mod or admin and ask to be added and you'll be able to access it.

[HarvestingInternationally]

i dont think they came with a LS in the front...if it says 3AL on the door sticker on the lower right by the driver side door the rear has limited slip..i have a FX4 and it does in the rear

[N8USCG]

Mr. Thompson thank you sir i just asked to join. ill update tomorrow if i find any amplifying info on my trucks condition