[Tom Goldman]

there are no different series gears for a 9" like 10 -12 bolts or Danas have .
The spool will be the same ,but the pinion is probably the large 35 spline type so your 5.00 gear will need to be a 35 spline or you will have to change the yoke and use a collar and spacer on the stock size pinion shaft. ....... Preload does not change with the gears ,once it's set it's good unless you replace bearings.
pinion depth is changed with shims under the pinion support. ..backlash and spool bearing preload is done with the threaded adjusters.