[Opserty]

You need to add a join to the thread queries.

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Hook Location: forumdisplay_query
PHP Code:

PHP Code:

$hook_query_fields .= ", user.usergroupid";

$hook_query_joins .= "LEFT JOIN ". TABLE_PREFIX ."user AS user ON(user.userid=postuserid)"; 


You should then be able to use $thread['usergroupid'] to get the thread starters primary usergroup.