CAT 436C 4X4 steering tie rod inner nut removal

Trying to replace the right tie rod and the Hydraulic power steering shaft is turning.
This front axle is a German ZF unit with the steering ram on the front. In the service manual it only shows the 2 wheel drive front axle. The 2WD has the steering unit at the rear of the axle, and shows a square nutplate between the hyd ram shaft, and the inner tie rod connection.
My unit w/4WD does not have the nutplate.
How do I stop the ram from turning ?????
Thanks in advance...
Roger
801-953-9123

CAT 436C 4X4 steering tie rod inner nut removal