Bulldozer problem

I have an old 1960's, I believe, Caterpillar bulldozer that I will probably scrap. It runs, but I think the undercarriage is somewhat worn-out. Anyhow, what I'm wondering is....what is this thing worth. I've been told by someone who has the same machine, it weighs 18,500 lbs. What would someone likely pay me for this, just a ballpark, as I have no idea. I know I could come out better if I sold it parted-out, but I'm too old to mess with that. I'm just concerned someone will come along and lowball me.