OVERHEATING

89 chevy c1500 5.7
I am lost.
It all started with some coolant loss here
and there. It gotten hot enough and
pressurized to blow the drain plug out of the
radiator. I replace plug. Flushed coolant
system (twice). Flow was good.   Drive ten
minutes. Overheat. Tried bypassing heater
core. Overheat. Took thermostat out.
Overheat. Flushed agian. Replaced
thermostat,water pump,heat sending unit,
the other sensor near thermostat( I forget
the name of it).  radiator,upper & lower
hoses. I have no smell of overheating and
the motor doesn't skip a beat. Oil is clean so
is coolant. Ran it a bit hot yesterday. After
an hr of cooling I did see water coming from
tail pipe. Then today when I left work atop at
the store (2mins down the raod). I came out
to see coolant leaking from rear of the
motor (passenger side)

Please share some input...