Xterra - clicking sound in 2WD from front right tire, no clicking in 4WD

I have a 2003 Nissan Xterra

The right front side of the car makes a clicking sound ?

? When driving over 20-30 mph

? Almost sounds like gears slightly clicking together

? The sound continues if I put the car in neutral above 25 mph

? There is no clicking sound under 20 mph

? A few times there was a large bump, like running over a small curb and the clicking sounds goes away until the next time I drive

? I can drive the car in high 4 wheel drive, return to 2 wheel drive and the sound goes away until the next time I drive again

? It does not make the sound in hi 4 wheel drive

What kind of garage should I go to ? what might be wrong?

Thanks for your help!!!

It sounds a lot like a sticky freewheeling hub. I don’t know what the exact arrangement on xTerras is, but most part-time 4x4’s have devices on the front wheels that disengage the front axle when in 2wd. In the old days, you had to get out and turn 'em by hand but nowadays they’re usually either vacuum controlled or use some sort of ingenious mechanical setup. It may just be a matter of taking them apart and cleaning and regreasing them, but you’ll probably need to get a manual and figure out how they work to properly diagnose them.