Try reverse flushing Disconnect heater hoses and try running a garden hose through in both directions.
Instualation of a heater core on a 1999 Ford Explorer V6, how do you install the heater core.
specs on how to replace a heatercore on a 1993 ford explorer
Basically behind and below the glove compartment , you can see where the heater hoses connect to the heater core at the firewall from the engine compartment
I'm not a mechanic / technician but I was looking at fordparts.com and comparing the heater cores for the 1996 Ford Explorer and the 2000 Ford Explorer and they show the same part number ( so apparently the answer would be YES )
Heater core is leaking.
It should be the same as my 1995 - at the firewall the heater hose nearest the drivers side is the inlet hose to the heater core
On my 1995 Ford Explorer with 4.0 L OHV engine , where the heater hoses are connected right at the firewall , the hose nearest the driver's side is the supply hose to the heater core , and the hose nearest the pasenger side is the outlet from the heater core. (Helpfull)
Behind / below the glove compartment , inside the plastic box with the heater core
Look behind the glove box, up under the dash.
Answer replacing the heater core on a 1991 explorer is a simple job and takes around 30 minutes. disconnect the hoses from core in engine bay. remove access cover located below the dash on passenger side. remove core, replace core.
could be head gasket problem. does your heater work? might need heater core , clogged up. do compression test. or bypass heater core and see if that works.
autozone.com has online manuals that give step by step how to