when i put it in 4hi it grinds and then i doesnt some time and its locked in 4hi not n so i quit using it but doesnt in 4lo and i always put it in n and slowest been going into 4hi was about 5mph but i dought that woulda hurted it but only when i floor it and also i dont no if this has anything to do with it but under jeep a cuple days ago and there was a line in ghuss vacline but it was cup while mudding like beraly holding on but also there is change in the 4wheel selector thanks in advance