[wilton]

I have a 1973 ford mustang with a ford philco radio and the speaker (original) has gone out. Is it easy to install a new speaker in the dash, it is the one speaker set-up. Thanks!

 

[searbhreathach]

Here's what you do, worked the same as my '71.
Remove the Dash Pad (roughly 8 screws along the bottom). The dash and the front metal plate will pull out easily. Then you can get to the speaker easily through the top.

I would recommend you replace it with a pair of speakers that mount in the same location instead of the one so you can get stereo. You can buy the set from any Mustang Shop (Paddock, National Depot, California Mustang, etc. or your local place). You will be happier.
Here's some examples:
http://www.restoremustangs.com/Dash-Speaker-262.html

 

[eder]

Many of them can be reached by laying on the floor of the car and looking up under the dash and pulling the speaker out that way. It's a tight fit but it can be done. Another way is to remove the glovebox liner and reach the speaker throught that way.

 

[aodh]

Yes! The grall should just pop out. The you unscreew the speaker and take wires off. Those in the back you go into trunk and unhool the wires and unbolt the speakers.