[Nelson58]

Will these queries restore threads and IDs of deleted users in 4.2 PL3?

If you want to do it manually, here are the queries. For the posts:

Code:
UPDATE post
SET userid = x
WHERE username = 'oldusername';
For threads:

Code:
UPDATE thread
SET postuserid = x
WHERE postusername = 'oldusername';

Replace x with the user id of the member whose posts and threads you want to reassign and oldusername with the username of the deleted user. Also if you are using a prefix for your db tables, then append it to the table names in the queries above. Hope it helps.