I have a 2005 ranger FX4 and when I am in 4 high or low the front end will make a clunking noise, it feels like the front end is disengaging for a second and then it hooks back up and clunks. It only does this while pulling a grade, hard acceleration or any other time there is a load dragging the rig down. If any one can help it would be apperciated.

 

mine does it too and nobody knows what it is

 

Sounds like a CV joint bent too much. But if it only does it in 4WD, then I'd suspect something to do with the front driveshaft. Also, check all the engine, trans, & front diff mounts.

Of course, the transfer case might be a possibility...

 

Mine sounds like the same thing...2 years ago my truck was still under warranty and I took it in and it ended up that the transfer case was destroyed inside. They ordered replacement parts and rebuilt it...I guess. It was fine for a year, and right after the warranty for the repair was over, it started doing the same thing again!!!!! It still does it...when in 4 high or low, at a decent rpm, it makes a horrible grinding/clunking noise and sort of skips. The 4x4 seems to be still working but not correctly. Just the other day my truck will not even engage into 4x4 high or low so I have a whole other problem now. But about the transfer case, I think the motor that engages it is having problems, maybe with the cable connecting it into the transfer case, and possibly it doesn't engage the entire way which causes it to grind gears as they are not fully engaged which over time wears them down and causes to do what ours are doing.