The play is in the short axle (left). The long axle is just fine with zero play. Looking at some random images I found on the web, the play could be in the tapered roller bearing. I don't think Nissan used a custom bearing so it can be serviced (I guess). The only way to find out is to take it...
The lefthand driveshaft has some radial play on the reduction box side. I can move it up and down for about 1.5mm. I'm familair with axial play but I'm talking radial play now. I always thought there was a bearing on the shaft where it sits in the gearbox. The righthand drive shaft has no play...