Will the radio from the 2001 and newer aleros fit in my 2000 alero? and is the wiring different?

ur talking the "ac delco" radio right?
to the best of my knowledge it SHOULD be fine, i believe it stanard radio equipment used for pretty much every alero. although honestly, i'd say forget it and go for an after market, i have a pioneer in mine that i had bestbuy install for me, head unit was about $130, and the installation was free, only payed about $40 for the "wireing kits". but now my radio signal isn't as strong as before, still good, but not as good.

good luck