i just finished installing the original am radio in my car and it sounds amazing. i have a 4 by 6 speaker for now and was wondering if i should use the oem style 4 by 10 or use the updated speaker with the dual cones, any ideas or preferences

 

For a stock radio I'd use the replacement 4x10 from any of the Mustang suppliers, such as Glazier/Nolan. These are superior to original speakers, and using the full-size 4x10 will improve the bass end of the scale over the 4x6 you have now.