not a clue. Dunlap was Sears' "second" line. they sold tons of it. go to Ebay and search "Dunlap tool" and you'll get 715 ads right now.
Sears' other "second" line was "Companion". I have no idea who manufactured either of them. probably find it at AlloyArtifacts.com
to further underscore my statement above about the early "vintage" hex drive sets, why hasn't this one gotten any action yet:
8-piece 7/16" hex drive 1922 Antique socket set manufactured by the New Britain Tool Company
amazingly good condition. (almost looks like it's been "restored")
$9.99 + $8.63 shipping. 0 bids so far. auction ends Monday, 12/28
http://www.ebay.com/itm/331736239036?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT
not
one bid yet? for a lousy ten bucks? really?