I have constant problems with this also (just under 200k miles with an
84 Trooper).  The permanence of each fix of the starter depends a lot
on how thorough the mechanic is in chasing down any shorts that are
affecting the system, whether they bother to properly tighten the
mounting bolts, etc. and also on whether you are getting regular lube
and oil changes,  Troopers are noted for getting into repetitious
starter trouble eventually.

My best suggestion is take it to an actual dealer mechanic, even if
that costs more, and demand warrantied repair (so that they'll check
into the things that actually need checking, like whether the starter
is trying to crank a stuck engine because of a bad bearing or whether
a chassis short is screwing up the electrical system, etc).