What is the name/type for this soldering iron tip?
There are a few of these available from an Ebay seller:

http://www.ebay.com/itm/Ungar-Soldering-Iron-Tips-9015-X2-/281868809328

Says they are for Ungar Models 9911, 9911as, 9370, 9380 and UTC 200 series Irons. 

Here is another reference:

http://www.waveroomplus.com/Vanier-Soldering-Tip-U610--Equivalent-To-WellerUngar-9015_p_2934.html