Jwpanz :
Is this what you're looking for? https://www.amazon.com/RCA-Compact-RF-Modulator-CRF907A/dp/B0014KKV7W/ref=sr_1_2?ie=UTF8&qid=1539617647&sr=8-2&keywords=coaxial+to+component
LOL. No dude by component speakers he's asking separate bass-mid-tweet drivers vs coaxial (one driver, 2 cones).
OP, once upon a time somebody told me he didn't like coaxial, but didn't explain why, am guessing independent drivers work better, and component is more desirable but in a car oftentimes u don't have a choice right, u gotta use what fits unless you are willing to "custom$$" it. Are u afraid your rear passengers are going to get better sound than the driver?
I wouldn't worry about it that much, 'cuz most people use the rears for "fillers" right. U will be "underutilizing" your rears but nothing should sound bad.