In my '51 I have a Kicker powered sub, 6x9's and the 3" dash speakers. Since I found a good deal on the powered sub, I decided to buy all Kicker brand, there may be better options for the price. I think it sounds really good.
You can get the sub refurbished half price here:
http://www.halfpricecaraudio.com/Kic...SABEgLmKfD_BwE
The 6x9's and dash speakers are ran through a cheap Kicker amp:
http://www.ebay.com/itm/like/1317352...&ul_noapp=true
Here are the 6x9's I used:
https://www.amazon.com/s/?ie=UTF8&ke...pphtrp5x_e_p19