+1 on that. The shudder occurs when gently accelerating from 75km through to 95km/h and it's because the torque converter clutch (TCC) solenoid can't make up its mind to engage or not.
It's not a common fault.
Take a look and see if the car's had a recall for the bonnet strap. If there's no bullbar up front, it'll have a sticker probably on the inside of the driver's door housing stating that IF you put weight on the front, you'll need a strap and stuff. If there's not been a recall on it, go whack your bullbar and winch on then take it to Nissan for some free HD coil springs.
Oh, the rear leaves will probably be inverted if they haven't been replaced. Not a warranty thing, we're looking at replacing ours with Sax triple-action springs.