The rivets holding the upper ball joint on my 90 4x4 were a bear to get out. The upper control arm is tubular instead of stamped... I think it's that way on all 4x4s in that model range (88-98)? Guess the extra thickness made them harder to get out.
Firestone quoted me $106 (1.3 hrs) labor to do that job... would have been worth every penny. Of course they were ripping on the part - $80. Got a lifetime TRW from Advance for $30.
Tom