Obnoxious whining noise cm 871 front engine

[Big red 09]

Hello I have an 09 isx 525/1850 and the engine had an inframe rebuild at 936000 miles and now has 953000 miles I brought up the noise in front of motor to service writer when rebuilding the motor but I don’t think I was taken seriously It is coming from very front of engine gear train not belts pulleys but in amongst the gearing This has been a very good engine mechanically and even emission wise and was told when engine was tore down that the inside was great condition Anyway the noise from front of motor is fairly quiet on cold start up but after about five minutes it gets louder and stays at same loudness all day I have read some things here as to oil pumps concept gears etc I am looking for some advice as to what this is I have put on 400000 miles on this truck and was no where near this noise Thanks in advance to any knowledge out there thank you