Similar to what Scrufdog mentioned, my 1999 5.7 had the coolant leaking slowly from the intake gaskets, the coolant seemed to flow downhill towards the rear of the engine and then drip down and burn off on the hot exhaust/crossover pipe.
I never really saw any coolant on the ground but often smelled coolant burning and had to refill the overflow can every now and then.
Its was kind of tough to see the fluid run down the back of the block there, a close look with an inspection mirror while the engine was warm and coolant filled did the trick.
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