When I was flexing on the stump, I had it in 4low. I parked it, switched to 4low, climbed the stump, then stopped. Then I backed down and parked it and switched out of 4low. Then I switched into over drive to drive back into the driveway and I heard this grinding noise, and I shifted into drive (still happening) and turned it off.

It's been fine since. any idea why? I'm scared to use 4low now..

 

You must have the transmission in neutral for the shift between ranges in the transfer case (HI to LO or LO to high). It helps to be slightly rolling. The grinding noise was likely the transfer case getting stuck between ranges.

 

I thought I read you had to be in [N] or park.

Well that makes me feel better!

 

Park could result in pressure on the internals of the transfer case which an old encoder motor may not be able to overcome. As a result, it could get caught between gears. Slightly moving with the transmission in neutral makes for a quick transfer between ranges.

 

Ok, I'll keep this in mind.