shifting to low range

I have a 95 with the insta-trac 4wd shifter on the floor. I know that you can shift while driving into 4wd high, but how do you shift to 4wd low? When I try it makes a weird grinding type noise. Is this normal, I know that the gear ratios are changed in low range so is this what that noise is. Do I need to be in park or neutral when I shift to 4wd low?

Thanks

Yes you do. When switching to 4hi from 2 hi all that happens is that the transfer case engages and the axle engages. When switching to 4lo, the transfer case actually has to shift. So, you need to put it in neutral or park to act as a clutch so it can shift.