Just recently found a pretty good solution for speakers in my 78 Fiat Spider that I would like to share:
http://www.partsamerica.com/ProductDeta ... yCode=3082
Checker Auto (Partsamerica.com) also known some regions as Shucks or Kragen has a 700 watt Stereo Speaker System with 2-10" woofers and 2- tweeters for $39.99
It has quick connect speaker wires and a handle. SOUNDS GREAT!!! and for $40 bucks what a deal.
It fits pretty nicely in the back seat and can easily be removed-- puts out a lot of sound. Heck, the box itself is worth the price even if you wanted to put in other speakers?
Check it out and let me know if this helps anyone?