Front differential quit

check front wheel drive axles at the wheels possible damage

most likely the front differential is defective,,, does park work on a hill with out e brake (does it roll?)

-Possibly time to replace new one.


Mai

Slapping sounds like a transfer case chain

Check the transfer case motor that engauges the front differential into 4wd.Sounds like this motor might be faulty or sticking.

Technically you do not have 4 wheel drive, you have two wheel drive (possibly three-wheel drive). When you engage 4WD you direct power to the front and rear differentials. The front differential is an open style which means that only one wheel will drive, and the rear differential is likely the same type which means that you will only have two wheels driving the vehicle (one front, one rear). If the rear differential is a "posi-trac" or "limited-slip", then both axles should lock and drive the vehicle (hence, three-wheel drive), but this style differential is not as common as it once was.

when was the last time you've checked the fluid level in the front differential?
Try this, quickly. these gears don't last long when the fluid level is low, and it's a real big job to replace the gears/differential housing.

I hope this helps, ask if you need anything.

Sounds like its either the front drive shaft, front axle joints, or the transfer case

theres a ingage and disingage sencer up in there sometimes it gets stuck and it sounds bad but if u bang on it with a hammer sometimes it will let go try that

drive shaft coupling ,check the rubber boot hasnt isnt split letting the dirt in as it sounds like it.better off with a real car like a jag