[Bentwheelbob]

Originally Posted by Alvin

From my MOTOR AUTO REPAIR MANUAL 1978:

Under Heater Core Removal section

1973-78 Firebird...

4. Jack right front area of car and place on safety stand.
5. Remove rocker panel trim on right side and remove screws holding forward of panel trim to attaching bracket.
6. Remove three lower fender bolts at rear of fender.
7. Remove four fender to skirt bolts at rear of wheel opening.
8. Remove two fender skirt bolts near blower motor area.
9. Pry rear portion of fender out at bottom to gain access to hose clamp on lower core hose and disconnect hose.
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My note & tip below...

Note: Be careful removing the Baked on heater hose from the htr core. It is easy to bend and/or fatigue the pipe to core solder area being overly aggressive with the removal process.

Tip: If you ever need to replace the heater core in the future you will need to remove the nut (engine compartment side) from the blower motor case hidden stud the is near the lower heater core case hose. You will have all others removed and or loose and not be able to remove the case W/O removal of this hidden stud nut.

Well the directions from Alvin's Motor Auto Repair Manual were pretty much dead nuts on. The only variations were that there are only two lower fender bolts and only three fender to skirt bolts in the rear fender opening. The hose is off and the nut has been removed from the stud. Now to disassemble the interior....