I would keep it if you want big frames. I rarely find any mountain bike frames that big around here and the one time I did need to find one we got flat out lucky. If it rides as nice or better than the Trek aluminum frame police bike I have from that era you will be very happy with that bike after putting some time into it. Like someone else has said clean it up get it rolling and ride it. It doesn't look like the paint is in too bad of shape to me from those pics. It will probably end up being worth more to you than whoever would buy it for the $100 or whatever you would get for it.