F-150 Grabs Hard When In 4wd

95 Ford F-150, 4wd, 4.9L, 5-Speed. When driving in 4wd, the front right tire grabs really hard like it is locking up or grabbing really hard, then releases. What could be causing this problem? Also, it pops pretty loud when it does this. Any help would be greatly appreciated. Thanks!

first thing is to check for a siezed universal joint in the wheel before you break a axle yoke. there is another one in by the differential on the right axle that you should look at too.