I have a 12 inch pipe wrench with a tapered handle that is threaded at the end. I have not found any discernible marks on it. The thin threaded end does not look beefy enough to have been used for a breaker bar extension. What was this used for?

 This is what an old pipe wrench looks like if you take the handle off.
It used to have a wooden handle.
    yours Scott

Oh cool. Thanks. So its probably pretty old. I have a few very early 1900's pipe wrenches that are all steel, no wooden handle.

If you look at the top two wrenches in this thread, you can see what that pipe wrench handle would have looked like, more or less, when all its parts were there: http://www.papawswrench.com/vboard/index.php?topic=9512.0