Head bolt, replace or not

[gogogsr]

Ok guys, so i just did the leakdown test and here are the results:
The tool i used is similar to this one (custom made):

You Tube

You Tube

Pressure was set on 50 psi on the left gauge, after plugging to the hose pressure drop to 40 and the right gauge reading was:
cyl : 31 =22%
cyl2: 36 =10%
cyl3: 35 =12%
cyl4: 35 =12%
cyl5: 35 =12%
cyl6: 32 =20%

I did notice a crackle sound on cylinder 4 and 6, kind of a metal gasket crushing. No bubbles in rad, no intake leak, no exhaust leak, just crankcase blow by, which considering the truck has 200,000 km on it seems fair. Remember that the compression was 170 across the board.

I'm thinking it could be the intake manifold lower gasket, what you guys think??
thanks guys

[gogogsr]

what do you think of this hypothesis: Intake manifold gasket is leaking from its water port directly into the runner, which then drop into the combustion chamber, hence the white smoke. Some of it pass through the rings hence contamining the oil just a bit.
What you think???