What I do in situations like this, is add text in there for a second so I can see what's going on:
HTML Code:
us:<if condition="$post['usertitle']"><div class="smallfont"></div></if>
rk:<if condition="$post['rank']"><div class="smallfont">$post[rank]</div></if>
th: $template_hook[postbit_userinfo_left]
Putting us:, rk:, and th: in there will help me find which it is. If that line shows up between us: and rk:, then it's the usertitle, if it shows up between rk: and th:, then it's a rank. If it shows up after th: then you've got a plugin using the template_hook 'postbit_userinfo_left' that is putting in the line.