Whining noise

[Refish]

Good afternoon! Driving an 04 Tahoe with 5.3L engine, 156,000. A whining noise started about 6 weeks ago coming from the front of the engine. The tensioner pulley as well as the alternator each were noisy when checked with stethoscope, both replaced. All pulleys and accessories also checked without a strange noise. The whine has continued. Pitch does not change with RPM’s and it really doesn’t get louder at higher speeds. No change in whine when turning steering wheel. It can be heard in park, neutral, drive, and reverse. Also noted in two wheel drive and automatic all wheel drive. The serpentine belt was removed and the engine started - whine still noted as usual. The water pump is about two years old. No engine codes noted on DIC. No change in performance or fuel mileage. It seems the whine maybe coming from inside the engine. 

 

What are opinions of source of whine? Any ideas?

 

Thank you for your time and expertise.