VAN Folks,

At certain speeds, 45-65 MPH, there is a distinct rumble to be heard on
almost all road surfaces [some road surfaces are so noisy they drown out
other noises].

Weird thing is it can only be heard from the drivers seat, not the
passengers.

87 syncro with a decoupler. I've only tried it decoupled. I suppose I should
couple it up and check that too.

Does the front drive shaft rotate even when decoupled, driven by the front
wheels?

Mike