Alright Syncronauts, Q & A time..

As a new owner of a syncro, I'm trying to determine if I have a terminal
problem or not.  When my transmission is unloaded, (coasting) there is a
whine coming out of the main transmission. Can't find a problem looking
at the oil.  Maintenance records indicate good attention. PO said the
problem started after new tires ( all 4 ). This whine is not coming from
them.  Any throttle and the noise goes away.  Speed dependant and
neutral dosen't help.  Seems to me to limit it to final drive
components. Any thoughts?
Thanks
Mark Rokus