Clunk going from rev to drive and stepping gas

If I reverse out of a stall, then put it into drive and go, I usually get a loud clunk noise from the rear of the Xterra. Now if I reverse out, put into drive and wait 3-5seconds before pressing gas to go, I will never get a clunk noise.. It feels as if the gears in the rear gets stuck out of place, then pops back..

Anyone with ideas on what it could be??

Thanks,
Eric

Check your driveshaft u-joints

Edit to add..

Also check the u-bolts that hold the rear springs to the axle.