My mother has a truck similiar to mine. 97 RR 4.6 Today she goes to drive and nothing.. Tranny will not engage. I go over there and after going thru all the gears I put it in Low. The tranny engages in Low Reverse and Low 1. That's it. I hear a very slight noise under the car (more like a spinning). Could not crawl underneath @ the time due to mud, but wanted to check on here first. Help is appreciated on this. Some sort of shaft I would presume? which one and difficulty in fixing.

thanks all