signs of salt water use, damage

[Tony Cruiser]

I may purchase a Crownline 240ls 2007 w/350 mag. & bravo 3 drive. Seller says boat was only fresh water use. Can anyone help with tell tale signs boat, motor, & outdrive are salt water used, how to see if damaged. Drive has some erosion on it just before prop & above prop on drive. Any help please.