[rpmerf]

#1 is to make sure you have good connections from your battery to the starter. I have a ground going directly from the battery to the stud on the back of the starter.

#2 is to make sure you have a GOOD battery. I thought I was having starter issues for YEARS. This winter, I got a new 750 CCA battery and all my problems are gone.

I don't think the number of teeth is important, as long as it is designed to work with your flywheel. This may be related though. There are 2 types of flywheels - 153 tooth and 168 tooth. They are different diameters, 168 is 14.13", 153 is 12.85". The starters use different bolt holes. 153 is typically straight across, while 168 uses the angled holes. This does not apply to aftermarket starters, as they typically have 2 or 3 sets of holes.

Looking at the 98 Tahoe on Rock Auto. It shows a 168 tooth flexplate. The bolt holes on the starter are angled. Looking at your truck on Rock Auto, looks like angled holes and 168 tooth flywheel. Notice on Rock Auto, it lists a direct drive and gear reduction starter for the Tahoe.