EXTREMELY bad vibration in the front!

[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

[F350Powerstroker]

I would jack it up and check the condition of you wheel hub bearings...Also I would pop the inspection cover and see if anything is going on with your ring and pinion gear since the problem is only occurring when you are lock in 2wd or 4wd... If it is a heavy thud you could have a loose pinion or something of that sort.

[N8USCG]

The problem was actually in the drive shaft. The double cardan joint was extremely loose causing a lot of play while the drive shaft was turning, put a new shaft in and no more vibration.

[F350Powerstroker]

Good glad you got her fixed. Awesome picture and thank you for your service!