No newer GM radios will be an easy plug 'n play install. The harnesses in your car was used in '89 at latest I'd say.
Most newer Chevy's have the same harnesses as each other, if you want to hardwire one of those into your car, that may help. Then you'd just have to focus on mounting it, which shouldn't be too bad (prob. just have to drill a couple holes at most). Make sure you know what you're doing (or whoever does it does).