What does the crest for the world war 2 343rd infantry regiment's crest look like?

I don't know, however that regiment was part of the 86th Infantry Division. It was in combat in northern Europe. The Division nickname is "Blackhawk". The division website is www.86blackhawkdiv.org There is a picture of the Division's patch on that website. See that site, you may find what you are looking for. Also wikipedia has information about the division. I found a photo of this DUI pin posted on www.usmilitariaforum.com. The post said this was a rare DUI. It is a BLUE shield with a diagonal Bar and a Lion in upper Right and a mailed fist in lower Left. The banner contains the motto "WE SHALL NOT FAIL". The link to the forum thread is: http://www.usmilitariaforum.com/forums/index.php?showtopic=19301&st=0&p=133868&#entry133868