Is this a old noise or new noise..?

Yes GEN1 Monty rearends are more aft to be set up 'off' then 'right'.. (My right..Not Mother Mitzu right.. Thats 0.03 but thats a mile in a half in my would ..) ..It sounds like the gear set is off.. But its not off far enough to kill a gear set ... Just it makes a little noise and the only people on the planet who here it is me and you ..

Whats a "over night" oil sample say .??

I need to add this to my last post .. You can not check (feel) a rearend with the wheels or drums/disks or driveshaft on the rearend ..fact...AND ,,,,,,, Testing a rearend on 'jackstands' get you no where..fact ..