Transfer Case troubleshooting - make a noise at 70 mph

Are you sure the transfer case had gear oil in it. Its like your differential it needs gear oil. If you let it run dry it will blow apart not to mention what it will do to your transmission.

Not sure but the problem could be with the transfer case. The transfer case uses a heavy double chain and as it wears it can make a noise.

Your tires are out of alinement. Get your car's alinement adjusted!

Harmonic balancer.

check the moter mounts..

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Check the disk brake pads. At slower speeds you can hear them squeak because there is less wind and road noise. The other possibility could be a bad u joint at the ends of the axle half shafts on the front differential. Check both. I really doubt it is the transfer case. You transfer case is engaged all the time. The axle is locked and engaged when you flip the lever by a vacuum motor on the axle shaft on the differential.

It's probably the chain in the transfer case. I had mine replaced at 150,000 miles and it cost $1500.00 to do a full rebuild. And that included them removing and installing the transfer case and a new yoke for the driveshaft.( Because the play in the transfer case grooved the old one.)

I'd guess you have a tire out of balance, it sets up a harmonic around 30 to 35 mph, and at twice that speed, or 70 mph. I suspect if you drove it at 120 to 140 mph, you'd find another one. Could also be a tire that has a belt that has failed.

How many miles on this set of tires, did you get a lifetime road balance on them? Hazard warranty? How soon before you need new tires. Need to take all of these into account, but need to correct the problem before you have a tire failure and a wreck.

Fluid Should Be Checked Just The Same As Engine Oil. Should Be Changed At Least Once A Year For Proper Service & Reliability. Should be Driven 10 Miles A Month In 4 Hi To Keep Lubricated. I Drive A 1975 Chevy K10 PKP FullTime 4X4 NP203 & A 1980 GMC Jimmy Lock-Outs 4X4 NP205, And I Drive Them Once A Month At 55 MPH For 10 Miles (On Pavement). Keeps The System Lubed Up & Moving. Have Done This For The Last 15 Years I Have Owned Them. KEEP THEM SERVICED. Low Oil Is A Transfer Case Killer. Also Put The Correct Type Of Fluid In, Each Transfer Case Takes A Different Type Of Fluid, Call Dealer Shop For Correct Fluid Type. Some Take Dextron III Or 10-40 Engine Oil Depends On Transfer Case.

is your universal joints out and that is where its rubbing?
running different size tires on a all wheel drive is a big mistake it can burn out the transfercase