Sorry I’m new to this and new to jeeps in general, just bought my first Jeep it’s a 99 grand Cherokee limited 4.7 Quadra trac 2 with 112,000 km on it it worked great up until about 2 weeks ago after driving on the highway for about 20 minutes I tried to climb my friends snowy icy driveway not overly steep but a little in reverse and it it just spun the back wheels, front not engaging at all, I turned around and drove up forward and with some rear spinning I made it up.... when I got up top where it was flat and there was some room to play with it the front was now engaging but with some noise similar to the abs traction control noise in a newer vehicle ? So I let it sit for a few hours and tried again, worked perfect no noise no hesitation went down the steep driveway and tried to reverse up again, no issue climbed right up, drove back home on the highway nothing out of the ordinary everything works fine, sat overnight and tried again in the morning no issue worked as it should, again drove the highway for 30 minutes to my mechanic and same issue get into some snow and spin making the same noise put it on the hoist checked over driveline can’t see any visible problem, put the Jeep in gear while on the hoist all wheels spin no noise no issue went into some snow and spun the tires no noise, drive back home get into some snow noise is back loud and clear, so whatever the issue is it’s only after traveling at higher speed for a certain amount of time I drove all around the city at low speed for over an hour and went into some snow spinning tires with no noise no issue, I hope somebody out there can help me find somewhere to start I had some say transfer case but I just flushed it and it’s still the same and when it’s driven around city speeds there doesn’t seem to be any problem yesterday I climbed snowbanks and went through fields full of snow in low and high range with no issue no noise ?? I have no idea where to go from here, any ideas are greatly appreciated!!