Variable grind/spin noise under feet.

Ok, here we go. I have had the front and rear diff, checked, 2 new transfer cases, new gears in back, new pass cv.

the problem started while driving with a heavy load and towing. It sounded like the sound double at one with a big EERR. I pulled over, stopped, started again and it was gone and did not return till 500 miles later and then became more and consistent.

I found that if I engaged the 4wd auto button, the sound would vanish immediately, though it would eventually come back.

We had a mechanic tell us our transfer case was bad and took off the front drive shaft and no problem happen for the rest of our 3k mile journey.

I took it in and was informed the Tran Case was bad and had it replaced.

Before I got it home, I noticed a vibration in the truck and took it back. I got sent to a dealership and got put through the ringer with 2 months nothing getting resolved and lots of money. Sent back to the first guy to replace the t case again and here I am still having the problem.

The grind has a few stages now and comes randomly or sometimes when I hit a bump. It can be subtle up to very loud, to the point it feels like there is resistance in my forward motion.

I also sometimes hear a high pinging when I am slowing, like metal bouncing on spinning metal?

All this vanishes instantly when engaged into 4 auto or the front drive shaft is removed.

The dealer said they put ears under and the sound was in the transfer case?

I am really ready for some real answers, thanks.