DDEC V 14L series 60 Oil loss HELP

Aight so i rebuilt this engine just over 75k miles ago. Truck been running solid since it's first trip otr, mpg between 4.5 - 5.8 loaded performance isn't a problem here. My issue here is that this truck has been loosing oil since the start (about 1gal/800 miles) , im aware of the break in process and that oil consumption is normal on a fresh rebuilt engine, but at over 75k miles the consumption is the same and im starting to get a lil concerned here. I have replaced the head (reman) and replaced 2 air compressors. I'm told to replace the turbo but it doesn't make sense to replace it since both cold and hot sides are dry. I even plumbed a manometer to the crankcase via oil dip stick to measure pressure and it reads 2in H²O at cruise and 3in H²O going up hills at 1800rpm (LOADED). Any input and suggestions is greatly appreciated. Thank you

 

I will remove exhaust manifold and inspect it