save_url error

You need to URI escape your parameters. In your sample, you're not escaping the whitespace in the destination, which is breaking up the pieces you're giving to curl, corrupting the command. That is, curl thinks you mean "PM" is another host you want to connect to.

Your curl command should probably look something like:

curl "https://api.dropbox.com/1/save_url/auto/615%20PM%20%231008928.PDF" \
 -H "Authorization: Bearer auth_token_key" \
 -d url="http%3A%2F%2Fwww.minnpar.com%2Fpartbooks%2FBACKHOE%2520MANUALS%2FALLIS%2520CHALMERS%2520BACKHOE%2520MANUALS%2F615%2520PM%2520%25231008928.PDF"