it depends on how it was driven and anything done to the motor. like nos. or anything.
but i would say in about 50,000 more is a good time to do a engine rebiuld.
because i also have a 89 jimmy 4.3 tbi diefferent but similar.
and it had 225k on it and got an engine rebiuld. and i paid about $3300 to fix it up. and since then it's runs like new again to me.
