TroyDairy, It appears that the major missing part is just the smokestack. There are smokestacks around still. There is no way of knowing the condition of the boiler from the photo. It could plumb shot, or may have had little use. An ultrasound or UT meter, would help if you were there. If the boiler is good, the engine is worth more. If the boiler is bad, keep in the back of your mind that new boilers are running $30.000+ these days.
Changing the subject, today would have been my dad's 120th birthday. We had a dump of snow overnight to help celebrate his birthday. He was a licensed steam engineer in Montana in 1911 at the age of 12. He never lost his love of steam engines. Gary?