depends on what kind of speakers, factory replacments or aftermarket, what kind of car?
Yes they can be.
Cerwin Vega are considered to be some of the best car speakers avalable.
You have to go purchase an aftermarket wiring harness. that will plug into the factory harness then you can wire it to the aftermarket radio.
Any aftermarket shop will be happy to do it for you
Most likely the speakers are rated for different 'ohms' (or resistance value) in the car stereo wiring. For example, the stock speakers could be rated for 12 ohm wiring, but your aftermarket ones could be rated for 10 ohm wires. The aftermarket speaker would not work, because there is too much resistance in the existing wires. So, either find replace your stock speakers with an OEM (original equipment - manufacturer) part, find an aftermarket speaker that will work with your current wiring, or rerun your speaker wiring (not terrribly difficult, but should still be done by a professional.) Hope this helps.
A 1983 Chevy Scottsdale truck uses standard 9" speakers. The size can be increased or decreased by installing aftermarket speakers.
The GMC stereo has amplified rear door speakers. When wiring up the aftermarket stereo, connect the blue wire on a GM aftermarket harness to acc power and the speakers will work. I did the same thing for mine about 5 years ago. Good Luck...
In the 1997 - 2001 Cherokee the front door speakers are 6.5 inch. However they do not match 6.5 inch aftermarket speakers.
go with aftermarket speakers, they are cheaper, sound better, and are usually made with better quality material.
Yes and yes
the deck/roof enclosure just pops out with gentle prying around the egdes after that its a matter of getting the right size/ohm rated speakers and wiring harness adapters to make it goof proof, you may have to drill some holes if the mount holes don't line up, most aftermarket speakers use 4 mounting holes and oem use two on that model. but it isn't really all that hard to do.