[iamtgo3]

Well as far as I can see there are two table you need to change Post and Thread.

Post Change would go like this.

PHP Code:

UPDATE post SET userid = '[I]posters userid[/I] ' WHERE username = '[I]posters username[/I] ' 


Thread Change would go like this.

PHP Code:

UPDATE thread SET postuserid = '[I]posters userid[/I] ' WHERE postusername = '[I]posters username[/I] ' 


NOTE - This is a suggestion please do not use it till someone who knows vBulletin verifies that it is right. I tried it and it seems to work.