Is a 2008 and 2010 GMC Sierra exhaust the same?

No, a 2008 and 2010 GMC Sierra exhaust system is not necessarily the same. While there might be some similarities, there are likely to be differences depending on the engine size, cab configuration (regular cab, extended cab, crew cab), and bed length. Even seemingly minor changes could affect exhaust routing and component dimensions. You'd need to check the specific part numbers for each year and configuration to be sure.