Compatibility is technically 98-04 Gen 3 M90. There is a Gen V M90 that is found only on Grand Prix from 04-present, while the Gen 3 can be found on Monte Carlo'* and Impala'* in 04. You can however use a 96 or 97 if you cap off three vacuum ports.
On rebuilding a charger, many places like Intense and ZZP sell the parts as well. But this guy ships super quick and super cheap. His site is also well organized for this stuff. If you have a charger, rebuild it and there'* no need to buy a new one. But the cost of the parts will outweight the cost of that charger you found.
Rolling Performance Home
The snout rebuild kit and rotor bearing replacement are the parts you'd need to rebuild the charger along with the SC coupler, 2 bottles of SC oil and red gasket maker . The gaskets for TB, SC (including o-rings) are needed to remove and replace the charger, along with a little coolant.