Ok gents, when replacing the upper and lower intake manifold gaskets I found a fair amount of what I am assuming is blow-by oil residue in the manifold. Truck has 210,000 miles so I assume this is to be expected.

Also noticed oil in a strange place, at the rear of the heads where they meet the block. What does this look like to you guys? I have no idea, can the head leak oil or have blow-by?

Also what can you do for the blow-by in the intake manifold other than replace the piston rings/rebuild? I was going to let if fly as-is because it still runs well.

 

You didn't say but a sparkplug in the photo tells me it's a V6 motor.
The oil in the intake likely is from the PCV system venting back into the intake from the calve cover. PCV valve may need cleaning or replacement.
Oil outside is a leak.
Check the valve covers/gaskets etc.
Good luck.

 

Yeah it's the 4.2 V6. Probably was the pcv, just replaced the pcv valve.