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yes
2 screws.
cracked heads or block
Often a knock when cold is caused by piston slap, which is pistons rocking in the cylinders until they expand in size when the engine warms up.
Could be a sign that the heater core is starting to leak
Does it quit shaking when it warms up? What engine and year of Aerostar?
Is it a lifter ticking?
Check for vacuum leaks.
crankshaft sensor
They are controlled by internal hydraulics so they will always 'free wheel'. As the engine warms up, the valving within the clutch actuates it. Sounds OK to me.
The type of surface that warms up the slowest is the "ocean" surface.