When engine cold 1st thing in a.m. there is strong vibration in rear of vehicle. on 2003 Toyota Highlander

Only occasionally first thing in the morning without warmup there is a strong vibration apparently from rear of auto within the 1st 1/4 to 1/2 mile. It stops after that. It is, however becoming more and more frequent.
All fluides have recently been changed including tranny.

Asked by for the 2003 Toyota Highlander
Did you have a rear differential fluid service? It's possible if so that it you could be missing a friction modifier from your rear fluid. Check with your point of service and ask them.