Noisy Dana 20

ok.. i just finished my 1970 postal jeep. i put in a T150 / Dana 20, finished getting the gears setup in the rear end and now that i have been driving it around i have noticed that the t-case has been making noise.. it only seems to be making noise when im decelerating and only around 50 - 55 if im going slower than 50 it doesn’t make any noise, im thinking its just the fact that i don’t have carpet in the jeep and im running really low gears in the axles. im running 5.38's and 35" boggers. the noise it makes kinda reminds me of taking two pices of sand paper and scraping them together but than again its really hard to hear clearly over the tires. it doesn’t make any noise at all when im accelerating and i haven’t noticed any mettle flakes in the oil. any ideas?  

Could it be a u-joint and not the transfer case?  
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pretty sure its not a u joint, i talked to a friend of mine and he says his atlas has been making the same sound since he put it in and when he called the factory they told him its a normal sound for gear driven t-case. thanks for the help im trying to give the jeep a good once over making sure i did everything right before i take on its maiden voiage, about 120 miles round trip not including the trail...  

Normal gear noise is typically related to speed only. The tone changes with speed, but not with acceleration and coasting.

The pitch of bearing noise will change when they get loaded or unloaded. They can be quiet when loaded and noisy when coasting. Their tone also changes with speed.

A u-joint's angle changes when going between accel and coast and it is typical to make noise during one condition and not the other. It is also very common to only occur in a certain speed range.

Warped brake drums or brake shoes that are not properly adjusted can make noises.

Worn enigine or tranny mounts or improper driveshaft angles can lead to over-angled u-joints, causing noise even though the u-joints may be new.  

the tone does change as i slow down but like i said its a little hard to hear it clearly over the boggers, the drive shaft in the rear is sitting at about 20-25 degrees which is almost at the max angle that the u-joints should be at.. as far as i have read. im a newbe builder so i still have quite a bit to lurn. reading what you said above it sounds more like bearing noise but im not 100% sure. if it is bearing noise do you think i should get it rebuilt before i take it out this weekend or is that common in dana 20's im sure mine probably has about a million miles on it. im supprised i can even hear the t-case, driving that jeep sounds like someone throwing a washing mechine down a flight of stares!
thanks for the help!  

In 2wd, the Dana 20 doesn't have much in the way of gears meshing and turning. In fact it was considered a huge improvement over the much noisier Dana 18. The Dana 18 had driven gears all the time because of its offset rear output. But the Dana 20's centered output doesn't require gearing to turn the rear ouput. Only when the Dana 20 is in lo and 4wd are there gears meshing.

But there are several sets of both needle and caged bearings that do spin in 2wd.  

think it somting i should be conserned with?