This radiator was for a 2006 cbevy Silverado 4 door with the 5.3 liter gas engine. The fit was perfect. No modification needed. It took me about 45 minutes to replace the radiator. It has helped fix my coolant loss problem that I had with my stock radiator. The end caps started to leak on the stock one (182,000) miles so it lasted quite a while. I would definitely purchase again if needed in the future.