Could my drive shaft bearing be the culprit?

My 2006 GMC envoy (114,000 miles and serviced on schedule)makes a sound, on
occasion, from underneath the truck while driving. It sounds like grinding/humming or
some type of winding sound. It seemed to be trying to shift gear. I suspected the
transmission. It checked out to be shifting good but had it serviced by the dealer
anyway. The shop suspected that the noise was from a front wheel hub bearing
assembly. Both were repaired. I heard the grinding sound 2 days later. Did some
searches and thought maybe the differentials needed servicing. Both were serviced.
After leaving the shop, I heard the sound again. The transfer case was not serviced. It
was said to be low but, no track 3 oil in stock. I will get it done within a day. it always
happens during acceleration. Previously, I thought it only made the noise when the AC
was on. That proved to be wrong. I achieved 45 mph heard the sound, took my foot off
the accelerator and the noise faded away. I hope this is a more helpful post. thanks!