You can check the top NITs for Mechanical Engineering below

National Institute of Technology, Tiruchirappalli

National Institute of Technology, Warangal

National Institute of Technology Karnataka, Surathkal

Motilal Nehru National Institute of Technology, Allahabad

National Institute of Technology, Rourkela

To check the closing rank of all the NITs you can refer below link

NITs cut off for Mechanical Engineering

Good Luck!!