Weird buzzing sound at 2000-2500 rpms

Hey guys, I have had my 2003 Toyota Tacoma prerunner V6 auto for a little over 8 months now, and as of recently my truck has started to make this weird buzzing/resonating sound between 2k and 2500 rpms. At first I thought it might be the skid plate, but it would make that noise if it were in park or neutral at those rpms too, and it doesn't. It only makes that noise in drive, usually if I am driving casually, and it shifts at that 2-2500 mark, it'll also make that noise in that same range if I am hard on the throttle and it doesn't shift at that mark. It's a short buzzing and then it vanishes at around 3k rpms. It could be nothing, but I want to ask some more experienced first gen owners if they have had the same issue. Here's a video. It happen right at the end of the video, and it's kind of faint, but you can hear it. No matter what gear it is in if I hold it at 2-2500 rpms it'll make that sound. edit: getting a second air of ears in the passenger seat it seems like the sound is coming from the right-most vent. same general area of where my dash rattles when shaken around too much (offroading and such) might be a washer or something vibrating somewhere in there.