i have a 420sel, and i want to take out my becker grand prix and get a pioneer or somthing, what do i need to do- can i use the factory amp

 

yes.

 

how would i hook it up

 

you won't.

you will let the technician do it for you. if you buy the radio, they will install it.

 

figured it out, thanks for nothin

 

Well, you can't please everyone.

 

true

 

giving the step by step instruction would be difficult for me on such less urgent cases.

a straight answer is all i can do. still the best advise is to let people who understand the system do it if he don't know how.