[crank182]

I had a similar problem with my blazer, the hubs would lock and it would feel like it was in 4wd but the front wheels wouldn't spin because the transfer case wasn't, the problem was a non operational vacuum pump. to test this locate the diaphram, it looks like a cruise control diaphram, it has a silver ring around it, and a line coming in and going out of it, you will be able to push the middle in and it will make a sucking sound, if it doesn't make a sucking sound there is a vaccum leak, try to put it in 4wd and then press the diaphram in and put a pair of vise grips on the line that is pulled back, that will engage your half shafts. If it doesn't work then check to see the front hubs are locking.