apb: If there is too much play in the bearings all you do is to tighten them. You loosen the split spindle nut allen screw with an allen wrench (8mm I think) and tighten the spindle nut until there is no play in the spindle bearings. You can do this by feel: Just try shaking the wheel gently and you can feel any loosness. When all the free is play is gone you turn the spindle nut about 10 degrees more and then you retighten the split nut allen screw.
Front wheel bearings on a 2 wheel drive rear drive are not rocket science but front wheel bearings on a 4 wheel drive or front drive are more complicated. I don't believe any gage is needed for 2WD rear drive front wheel bearings. I have been doing them for 40 years and never used a gage.
If the bearings do not make any whining noise, they are OK. They rarely go bad as long as thay have enough grease. You might add some wheel bearing grease in the hub cap before you replace it which will push the grease into the wheel bearings.
P E H