99 Yukon 4x4

[99Yukon4x4]

I just bought this vehicle, and it is pretty much decent shape. 199K, fully loaded with almost perfect leather interior, body is about a 7/10, and decent tires. I toying around last night while driving thru a few puddles from a tsunami that last about 5 minutes here in Florida. I put it in auto 4x4 to see if it would activate and work. When I got up to about 30mph, I got a really bad vibration and humming coming from the front end. I pulled into a shopping center, put it back in 2 wheel, and drove around the lot and it was gone. I then put it in 4H, and it did the same thing, but at a lower speed. I did notice on the highway in 2 wheel drive that I have a slight vibration at speeds over 60mph.

Now, I am planning on replacing the hub/bearings next weekend, with all the brakes, and changing out the rear diff fluid, tranny fluid, and xfer case fluid, as well as front 4 wheel fluid. With the vibration I mentioned, what else would be causing that so I can get it corrected. My wife and I may possibly be moving back up north, and need the 4x4 to work properly.

Thanks for the help!

Mike

---------- Post added at 10:34 AM ---------- Previous post was at 10:03 AM ----------

I just checked the fluid, and it is low and REALLY dark. So, obviously going to change that out. What else should I attempt to do, or what kind of fluid would be best to use for a vehicle with high mileage.

Thanks

 

[SunlitComet]

standard fluids as called out in owners manual. If you don't have one, here. http://www.extendedgmwarranty.com/owners-manual/chevrolet/1999-Chevrolet-Suburban.pdf