1995 Suburban 4 Wheel Drive

I just recieved a 1995 Suburban GM Brochure which I bought off of ebay last month. I was looking at one of the pictures which showed the floor shifter for the 4 wheel drive. The caption said "The most relied upon 4X4 system on the road, Insta-Trac lets you shift on the fly from freewheeling 2WD to 4WD High and back at any speed." Is this true or was it a mistake on the brochure, can I switch from 2WD to 4WD while I'm driving on say a wet road that intersects paved road? I remember one time I was shifting into 4WD, and I was stopped, but the car was on a slight slope, when I shifted to 4WD I heard a noise that sounded like something rubbing against something else, has anyone else experienced this?

I thought insta-trac was the thing on the newer Suburbans where the floor shifter was replaced with the push button thing on the dashboard.

I've shifted my '94 in and out of 4HI at speeds up to 45 mph or so with no problems. I think if you stay below 50 mph when shifting, you should be okay.

I shift my '95 in and out of 4WD all winter long while moving. All you have to do is take your foot off the gas enough to remove high torque from the drive train, and then don't expect the 4WD to engage for about 15 to 100 feet of travel. I always try to engage my 4WD about 30 yrds before I need it.