rumble at 65kmh

Ay up, got a new rumble at about 65kmh when on the power, sounds like its at the back but you never know.

no i havent even looked at ujs , wheel bearings or anything else yet coz its covered in sh1t and its cold, i have drained and nipped up the pinion bearing in the rear diff and topped up with fresh ep90 just incase as i rebuilt that a while ago and i know my workmanship is crap so just wanted to be sure it wasnt loose.

any ideas?

I have the same problem on a d2. I am thinking its down to props but have to wait for the rain to stop to check