Hi, welcome to Just Answer.
The heater core on this car is a very involved task and requires the complete removal of the instrument panel...so before begining you need to have experience in vehicle interiors and electrical. Most of the procedures listed for this model are written assuming the technician has this experience. It also requires you to evacuate the air conditioning refrigerant since the a/c core will also be removed. The total labor hours for this job is 4.2 hours, at the dealer this job would cost just about $580.
REMOVAL & INSTALLATION
See Figure 1
Remove the knee bolster and the lower trim panel.
If equipped, disable the SIR system.
Disconnect the negative battery cable.
Remove the steering column support bolts and carefully lower the steering column.
Remove the cluster bezel screws and the bezel.
If necessary for lens replacement, remove the lens screws and separate the lens from the cluster.
Remove the cluster mounting bolts/screws, unplug the electrical connectors and remove the cluster.
If removed, install the lens to the cluster.
Position the cluster and engage the electrical connectors.
Secure the cluster using the retainers and tighten to 16 inch lbs. (1.8 Nm).
Install the bezel and tighten the screws to 29 inch lbs. (3.3 Nm).
Raise the steering column and tighten the supporting bolts to 20 ft. lbs. (27 Nm).
Connect the negative battery cable and enable the SIR system, if equipped.
Install the knee bolster and the lower trim panel.
See Figures 1 and 2
For 1984-88 vehicles, perform the following:
Remove the cluster bezel, including the tilt wheel lever.
Remove the center bezel from above the console.
For 1989-96 vehicles, remove the instrument panel trim plate.
Unfasten the control panel-to-carrier attaching screws.
Rotate the control panel for access to the electrical connectors, control cable and vacuum hoses (if equipped), then unplug and remove the control panel from the vehicle.
Installation is the reverse of the removal procedure. Tighten the heater and A/C control screws to 35 inch lbs. (4 Nm).
O.k. I'm opting out so another Expert may want to help you...but if you have the info, you should be able to complete the job...and if it doesn't make sense...I would personally not attempt it.