Hi Doug, how are ya? My Merc. 9.9 (2000) locks down in neutral and in reverse and is unlocked in the forward position. If you flip the shifter and follow the linkage down that heads toward the gear box, you will see a smaller piece of linkage come from the main linkage about a foot down from the top. It goes up and over the mounting frame (toward the boat)and down to the locking tabs ( a double hook set up) right at the bottom of the mount. Hope this helps

Good luck

Doubletake