What is causing grinding noise after replacing starter on my 1997 F-150?

A grinding noise after replacing the starter on your 1997 F-150 could be due to improper alignment between the starter gear and the flywheel, often caused by an incorrect starter installation or using the wrong starter for your vehicle. Additionally, the starter gear may be engaging with the flywheel too aggressively or may be damaged. It's also possible that debris or worn components in the flywheel are contributing to the noise. It's advisable to double-check the installation and inspect the flywheel for any issues.