chirping sound peterbilt

I posted problem a while back but still havnt got rid of the noise. trucks 95 pete n14 super 10. chirping seems to start when engine is warm, between 1500 1700 rpms. when you are pulling a grade. does this in 5th through 10th gear. if i keep it in high gear pulling a grade and keep after the throttle it will slowly fade when it gets around 60-62 mph. but will come right back at top of the grade. things i have done. swapped tranny. motor mounts new clutch had this done idk if they change pilot bearing or surfaced flywheel. i took shop parts said throw out bearing was out of old clutch other than that it looked new. new bearing and seal in rearend which was leaking. i have also shimed pto. also tighted up every nut bolt bushing i could find that was loose. also adjusted ride height on suspension and cab. i have had two mechanics look truck over and they say everything looks good but cant pin point this sound. thanks for looking any help will be appreiciated at it is sp loud it drowns out the radio.

 

I have checked all the hoses and clamps on intake side and checked turbo also. I can believe it could be head gasket the middle head bubbles oil at the gasket. showed it to mechanic , he wasnt too conserned. truck has 705000 on it its my grain hauler so it dosnt get drove everyday but gets ran alot certain times of the year.

 

would a blown head gasket only chirp at higher rpms and seems like higher gears in tranny? and would it stop like it does when keeping the trottle to it climbing grades then ehen strain lets off itvstarts again at the top. is there any way to see which head gasket is problem? or if a bolt broke would it be easy to turn?