Conversation Between CraigW75 and Mark Kovalsky

I took the pan off of the transmission, no shavings, no burnt smell.
I drained the transfer case, barely any fluid at all..and what was there was very dark.

The only thing that confuses me, and I forgot to tell you, the OD light was blinking earlier. We were on our way home from a 120 mile round trip, the OD light started blinking about halfway back home, I didn't notice until we stopped at the gas station. When I started the truck back up it didn't come back on the rest of the way home, and shifted fine. We got home, it sat for 30 minutes and when we left home it still shifted fine. About 10 miles later I pressed down on the gas to go up hill and nothing, no power to the wheels at all. Shocked I thought I'd lost the driveline. Instinktively I put it in park, GRIND, I shut it off. I got out and looked, nothing odd on the outside of the truck, no OD light blinking. I shifted through the gears, nothing...I decided to see if the 4x4 would engage, at this point I thought if it's the transmission, nothing will happen anyway. I hit 4x4 low and GRIND again we had power to the wheels.

My guess is the transfer case.

I have a 1998 Expedition with a 4R100 transmission that is acting up on me.
It's shifting at an extremely high RPM 1-2 and 2-3 but will cut the transmission out at about 5500 rpm, and grind when put into park...If I shut it off and put it in neutral change it from 2h to 4x4 low it will re-engage and let me do it all over again from 2h. Is it a dead transmission, or transfer case or what?
When it's "disengaged" I hear a rustling noise coming from the connection between the two..I'm lost at this time, please help