Brian, My company owns a fleet of '99 Blazers. Keeps me busy! The
pitman arms need replacement on a regular basis here. The design is
very poor.

First remove the front plastic panel that looks like a skid plate, and
the left front wheel. Break the pitman arm loose from the steering
link. Then remove the 3 steering box bolts from the outside of the
frame. Working from the front, you can pivot the box enough to get a
pitman arm puller in there to get the arm off. It is a pain, but once
you do it, it is not that bad. Air tools are a big help.

Good luck. James