Sporadic Loud Whirring In 3rd Gear - Transfer Case?

'62 CJ5 with what I assume is the factory trans and transfer case (D18?) and OD
In 2wd, street driving, warm temp, at around 45mph, a loud metallic whirring sound has been emanating from the trans. t-case area recently. When it's happening, I can feel the vibration thru the transfer case shifters, not really the transmission.
It's not the grinding, crunching sound that a wheel bearing would make that gets louder under load - more of the sound that a shaft vibrating in a worn housing or in a worn or seized bearing would make. Totally quiet, then depending on speed, a full-on whir. I say 'whir' because it's the sound of something turning, not something vibrating or a loose part rattling.
It doesn't get louder as the speed/engine rpm increases. It's either full on, or silent. It also doesn't appear to be contained inside a case..not muffled. In the past, slowing down or depressing the clutch would make it stop. Yesterday, it came on and continued after slowing and depressing the clutch.
Admittedly I haven't checked the oil levels and I know that I really should do that immediately. I'd like to think that the racket is simply from low oil in the transfer case, but that's probably optimistic. Maybe low oil caused this, but adding oil probably won't fix it (BTW, does the trans share oil with the transfer case?)
A buddy of mine has a lift, but he's a good 40 minute drive at non-highway speeds. I'm not going to drive it there with this going on.
Does this sound familiar to anyone?
Any thoughts on what I should check first after I confirm oil level?

 

I would guess it's a worn out intermediate shaft . common in the D18
if you drop cover see if it moves side to side . up and down

 

This isn't really a gear whine, or grinding sound, it's an all-out loud, rattling whir that is either full-on or silent. One other thing, the parking brake has been disabled for whatever reason. It looks like the assembly is there, just no cable. Could loose brake components in the housing possibly cause this racket?

 

Check u joints first. Always look to the easiest solution then go from there.

 

absolutely and probably is..

 

Got under it with 5 quarts of GL4. Hard stuff to find. I thought I'd have plenty left over, but not the case. Drained the transfer and not much came out. Concerning. Topped off the trans and f&r differential. All were low. Not good.
I checked the u-joints and they're decent. Even though disabled, the trans brake housing seemed to be intact with no signs of fresh metal to indicate things rubbing or bouncing around. One thing that gives me concern is the output yoke(?) for the front drive at the transfer case. Most everything has a thick patina of greasy oil on it...except this. It's totally dry. I can only assume that it's been heating up considerably...enough to burn off the oily covering. I can only imagine a spent bearing heating up the shaft and the yoke. Instead of binding the shaft, if the bearing race has deteriorated to the point where the shaft is sloppy, it would totally explain the sound. I haven't driven it to test to see if things have quieted down...
Any thoughts?

 

I’m sure it’s a lot quieter now with oil in the gear boxes. Do you have free wheeling hubs on the front? If so just unlock them and that u-joint won’t be turning. Looks like that joint could use a squirt of grease.

 

If you have an overdrive and ran it that low on oil it is now toast. They simply do not live without oil.

 

Check fluid levels. If ok check u-joint condition and u-joint angles. Any of the above will cause the conditions you describe.

 

That dry looking yoke is normal. I don't think anything is getting hot enough to burn off grease. On the transfer case side, there is an oil slinger that keeps the oil weeps from creeping to the yoke, and the driveshaft has a normal patina from grease weeping out of the sliding joint. Rotating forces just help keep the yoke dry.
Your low gear oil in the trans/TC is where your noises are likely sourced from, especially the intermediate gear in the TC. Things will likely quiet down, at least a little, once you drive it with full oil levels.
-Donny

 

A few miles after adding fluids/topping off the transfer case, this particular noise has completely stopped. There still is the subtle gear whine, but I think that's the nature of a 56 year old beast. I do think that some degree of damage was done however. Low fluid levels that cause a racket like that has to have some adverse effects.
Anyway, lesson learned: keep the drive components topped off and check periodically.
Thanks again for the helpful replies!

 

I think I see what you mean..the U-shaped mount in the upper left corner of my image should look like this?:

 

I am not sure what (if any) difference it might make, but pictured below is how I set up my transmission/t-case mounting per the original for a V6 model. It does use the same mount as the F-head engine mount, but it is bolted to the side of the frame with an angled piece going from the mount to the t-case. I figured it was probably key to get the adapter plate under the transmission parallel with the cross-member. Not sure if anyone makes or sells the angle piece?

 

I love that.

Jeep engineers:
"What are we gonna use for the mount?"

"How about an F-head motor mount, cocked sideways so it fits inside the frame rail?"