Which steering box do you mean as havent heard of "avenger" before?
If this is the squareish manual job there is a nut and grubscrew on top of the vertical shaft for adjustment and over centre drag.
I stripped mine down and replaced all the bearings and seals then adjusted per the Chiltons manual, worked fine for me even with 33x10.5 15s fitted.
It's not the best box in the world as steering is quite heavy, but as I dont have the dosh to fit power steering I just rely on the large diameter steering wheel, brute force and a strengthened steering box bracket.