2000-2005 Yamaha F40B Outboard Service Manual, Page 342Get this manual
(3) Install the backlash indicator onto the drive shaft (16mm (0.63 in) diameter) (4) Install the dial gauge onto the lower unit and have the dial gauge plunger contact the mark on the backlash indicator
Magnetic base attaching plate 90890-07003 Dial gauge set (1) YU-0309790890-01252 Magnetic base YU-34481 190890-06705