Heater core how can I replace

HEATER CORE

Remove 7 screws attaching heater access cover to plenum. Disconnect vacuum source. Leave vacuum harness attached to cover. Remove cover. Remove heater core from plenum. To install, reverse removal procedure.
PLENUM ASSEMBLY
Loosen instrument panel attaching screws and move instrument panel back to access plenum. Disconnect and plug heater hoses from heater core. Remove glove box. Remove floor air distribution duct from plenum assembly. Remove 2 nuts retaining left end of plenum assembly to instrument panel.
Disconnect temperature control cable and vacuum hose connections from control panel assembly. See Fig. 2 . Disconnect source vacuum block, which is secured to right heater core cover. Pull heater case forward to disengage 3 case studs from dash panel. Lower plenum assembly, and remove assembly from vehicle. See Fig. 3 . To install, reverse removal procedure.
Fig. 3: Identifying Heater System Components
Courtesy of FORD MOTOR CO.