1996 EB AWD V8 w/247K miles.

I'm getting what I call a synchronous vibration which appears to be coming
from the front wheels.  The vibes increase and decrease with the speed of
the vehicle, but disappears completely whenever I turn to the right.
Otherwise, the vibes are constant while going straight and in left turns.

I'm not getting the usual clicking noises associated with other cars I've
had with CV shafts which becomes more pronounced during turns.

On another note, is there an easier way to R/R the front differential fluid
other than remove the Diff cover?  The top three bolts look to be a pain to
get to.

Vito