It's something in the configuration for vBSEO and the way it re-writes the URL for your profile. Normally it would be this:
[noparse]http://www.stangnet.com/mustang-forums/members/member.php?u=151384[/noparse]
After the URL re-write it should become:
[noparse]http://www.stangnet.com/mustang-forums/members/84t-top[/noparse]
For whatever reason, it's re-writing the incorrect profile and completely omitting the 19 from 1984t-top's username. Shoot a PM to timeless2, he'll look through the settings in the admin control panel and should be able to get you fixed up. If not, you could always choose another name and have yours changed, which should also resolve the issue.