The nut is threaded onto the front shaft. It is an angular wedge inside and as it tightens, it compresses the spline surfaces to facilitate zero backlash.
When you state "Facing the rear " ..you can be facing it either from the rear of the car or from under the car...so your orientation discription is the problem. Alway state direction as "Direction of Travel"
And right/left side on a car is always from the DRIVERS POSITION..thereby eliminating confusion for RHD and LHD vehicles and if you are in front or in back of the car. This eliminates any mistakes and is normal orintation procedure.

Look at the threads that the nut turns on ..It is RH Thread and turns as any standard nut does ..you tighten CW and loosen CCW. So, looking at the driveshaft in "Direction of Travel".[ Looking Foward from under the car} You loosen the nut by turrning it CCW. That will release the tension on the splines .
You are turning the nut the wrong direction, if I understand your R/L orientation discriptions correctly.

By turning the wrench as you state "to the left side of car'", you are tightening the nut and moving it foward. The more foward the nut goes , the tighter it gets.
You have the CD...look at intermediate bearing assembly and you can see the wedge shape design of the slide nut right in the diagram.
You tighten the nut, you tighten the backlash..you loosen the nut, you loosen the backlash...simple...

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A Dalton