Guess this mean I need a heater core

Hey Keystone,

Take the heater hoses off and by-pass the heater core by running a small length of hose between the outlets on the manifold and water pump, or put a piece of pipe between the two hoses after you remove them from the heater core inlet and outlet nipples.

Fire up the engine and see if you still have a leak.

Also, if you have a compressor, force air into one side of the core ,It will push remaining coolant in core back out through the other open nipple.

With no coolant left in the core, if you still see liquid on the floor , you will know its not the core.