It’s hard to hear but it’s a low growl, almost similar to the sound of a Jake brake. Happens on deccel, louder in gear but still makes the sound with clutch in. Most noticable in 4th gear when engine braking. Is this a bad pinion bearing? Regear was done slightly longer than a year ago. The bearings should be good. Had the front diff open and there was some metal but seemed normal since it was the first time I had it open since the regear. Any ideas?