What work does the motor need ??-----In 1999 there were troubling times for OMC.-----May not find a 99 specific manual.----A 1997 manual would likely be the same.
If this motor had water inside on the bearings for 2 weeks you may have major rust damage on bearings.----Some will argue, but I think this unit needs to come apart for inspection.
Here I would simply take the lower unit apart for inspection , repair as needed and re-assembly.-----No manual needed and no need to buy any parts.-----These units are simple , well engineered and reliable.----Your location ?
Pull the flywheel.-----Inspect anti reversing spring.----Inspect drive key on bottom of rotor.-----Motor is always in FOWARD when not running.-----With 12 volts applied to green wire it shifts to NEUTRAL after just 1 turn of the flywheel.