amplifyers maybe?

[slowbob]

i have a 2003 ford ext cab f-250 w/ a stock radio single cd/ casette player. i just added a pair of gxr4 speakers. Will i need an amplifyer???

[Jstas]

No, you don't. Some will say you do but if it isn't in your budget, you can run them off of deck power or even the stock stereo. The speakers will not be performing at thier absolute maximum potential though.

You should be able to splice into the factory harness. Many companies out there now make wiring pigtails that plug into the factory harnesses and allow you to connect your aftermarket speakers to the factory stereo without butchering your wiring harness.

However, an amplifier is recommended. I would not worry about it right now though. It seems you are keeping your factory stock stereo and n amplifier will work with it but, not as well as it would with an aftermarket stereo.