I'm not exactly sure on the '78 dash, but if it's the same as the '81 dash, it's not a big project at all. There's just a little cover at each side for the speakers on top of the dash. Just get a shorty flathead screwdriver to pry the cover off. It's held on with tabs if I remember correctly. Then it's just unscrew the screws holding the speaker in place, disconnect the wires and put the new one in. I changed the dash speakers in my '81 in about 20-30 minutes.
Don't know if this helps or not, but I hope it does.
Why do you want dash speakers? I pulled mine out of the 74 and they fell apart in my hands. I put in some exspensive kick board speakers and then ordered the rear speaker box for the back, new stereo with remote cd. Now it looks stock but sounds great.. Think the sun really does a number on the dash speakers.
Not a hard job to replace but I found the clearance in the 82 didn't allow for a good quality speaker. I'm considering doing what Wamp suggests and replacing with kick panel units.
By the way, I bought the upgraded direct replacement from MA and fried it in a week. ad And I only listen to Classical music
I replaced the dash units in my 77. Just a couple of screws, the vent duct and a light that connects to the back of the lower dash.
You can get good quality units to add. While you're at it, you might want to replace the right as well. This involves taking off the inner windshield trim, removing the 1 screw that holds the upper dash pad in place and lifting out the pad.
Rich, You shouldn't need to remove the dash pad as the little speaker doors pop right off. You will however, need an "S" shaped screw driver to get at the back screws up against the windshield. You can get decent upgraded speakers that will fit right in the same holes but if you want to get really crazy with high power speaks, you won't have the available depth in the hole. I upgraded to Jensens and the sound improved dramatically. Be patient, and careful with the speaker doors. Sometimes overexposure to the sun will make them brittle.