Going by the service manual:
Fully apply Parking Brakes and leave brakes applied until adjustment is complete.
Mark Tensioner Rod 6.5 mm(1/4 in.) from edge of tensioner bracket.
Tighten adjusting nut at equalizer until mark on tensioner rod moves into alignment with tensioner bracket

Trying this method I have the cables tight enough to play a tune on them and the mark isn't moving into position.
Any suggestions ?
New Rear park brake cables, new break shoes , wheel cylinders - everything cleaned ,lubed and brakes adjusted.

 

Not sure how much force they want on the e-brake to consider it 'fully engaged'. My thoughts are, if you have as tight as you think it's gonna get, see if it will hold the truck in place when you give it a LITTLE bit of gas. If it will, call it good. Re-visit the adjustment in a couple months. (if you use your e-brake regularly) The new cables will stretch some.

 

Ok, Thanks !
It does hold to 800 or 900 RPM, so I'll take your advice and leave it as is for now.
I don't hardly ever, actually use the parking brake, but I do want it to work as it should, when I do use it.