differential and carrier bearings are very common in most endeavors. 04-06 is it a humming bearing noise?
What you are going to need to do is have them elevate the vehicle again, but with someone inside the truck to 'drive' it while it is in the air. Being an AWD model this makes like very easy for finding rotating noise like you have since all four wheels will rotate in the air.
With the vehicle elevated and a helper driving the vehicle at least 30mph so it is into the noise range, they are going to need to take a stethoscope to confirm the failure point. Stethoscopes are very cheap and they should not be without one anyway. If you/they need to pick up one, they can be had usually for under $10.
They will want to start by probing the rear wheel spindles right up against where the axle goes in to the back side of it. This is the housing that the bearing is stored inside. Compare left to right and front to rear; if you are in the speed range when the noise occurs, the stethoscope will make it abundantly clear as there will be lots of noise in your ears... it should be dead silent.
If the bearings all check out silent, you would then need to move to the differential and the carrier bearing (in case you got a new bad one). Realistically though you will probably be dealing with 1 or 2 rear wheel bearings, they are extremely common on the Endeavor, specifically 04-06 models.
Regardless, it will be very clear the issue once the stethoscope is used; the only noise that you will hear at driving speed like you describe and not be heard when elevated is tire noise (cupping, scalloped tires), however since you have new tires this certainly won't be the case.
If you find the rear bearing(s) are an issue, they take about 20 minutes each to change as they are complete hub assemblies, no pressing required. The bearings run about $200 each.