I am thinking the bolt in ball studs are aftermarket, so you will not find the torque value. GM peened the ball studs in except for the 55-59 trucks which used the more modern tie-rods.

Here is the last page of the '55-'59 GMC shop manual, steering section.

http://chevy.oldcarmanualproject.com/gmc/5559mm/5559mm011.html

Here is the start of the tie-rod section,

http://chevy.oldcarmanualproject.com/gmc/5559mm/5559mm009.html