Ok, upon further investigation, the replacement heater core has one additional row and about 5 more fins/inch. So maybe heat output about the same.
I added some tips in below to these instructions.
1. Drain the radiator; refer to «Section 303-03».
µ 2. Disconnect the heater water hoses from the heater core. For the heater hose coupling disconnect and connect procedure, refer to «Section 412-00».
Looking from under the hood, the hose on the left is tough to get apart. I had to rotate the hose to access to the pinch clip cause you just can't your fingers in between the hose and the heater box to squeeze the clips.
Remove the plastic clips from the heater pipes before trying to pull the heater core out.
3. Disengage the stops and lower the glove compartment door.
I removed the glove box with the 3 screws from underneath. Took totally out of the way.
4. Remove the electronic blend door actuator and bracket assembly.
This is the vacuum actuated blend door rod actuator. Pretty easy to remove, just one screw, unplug the vacuum tubing. Tilt it toward you and unhook it.
5. Rotate the blend door actuator and bracket assembly.
6. Remove the electronic blend door actuator and bracket assembly.
This is the white box on top of the heater box. Unplug the wire connection and then gently pry up on the white box. It is held in place with plastic pins and snaps down onto the black bracket. The electronic box and bracket are two seperate pieces. Once the box is off the bracket there are 3 screws that hold the bracket to the heater box. You have to remove this bracket before attempting to remove the heater core because this bracket actually holds the heater core pipes toward the firewall. You can't get the heater core out with this bracket in place. Trust me on this one.
7. Remove the screws.
8. CAUTION:
The heater core
cover must be raised vertically before removal to avoid damage to the heater core housing.
There are about 6 to 8 screws in this cover. Remove the screws and lift the cover vertically. The cover on mine had some silicone gasket maker around it. I will silicone back in.
Remove the heater core cover.
9. Raise the heater core cover.
10. Remove the heater core cover.
11. Remove the heater core.