2006 F-250 Viberation????

Update of vibration problem: Took F-250 to local Ford Service Center. Technician took a computer vibration analysis road trip and determined (1) the left front wheel bearings were bad (Hub) and required replacement and (2) both upper/lower left and right front wheel ball joints were going bad and required replacement. Work was completed and I immediately departed with truck on a vacation trip.. The exact same problem they claimed they fixed still exists.. rumbling vibration that starts at 40 mph and stops at 55 mph. I took it back and they now claim it is road noise but it happens all all road surfaces.. super smooth or rough.. Happens when coasting down hill with no acceleration or power being applied. I now have another appointment next week with same dealer for them to re-look at the problem. After having spent $1800 (service contract insurance) with them on this vibration issue without them correctly identifying and fixing the problem is disturbing! Will follow up as plot thickens..