jjstein:FWIW -- Put this idea on the back burner: If you get enough complaints on the "broken link" feature, instead of fixing "15,000 dead links", my suggestion is to generate a cross-reference and run a search & replace on textbody. I've done similar work on larger data stores than this; it's not that big a job.
StorkBite: I believe that we may be able to "trick" CS into taking you to the right place. This will require remapping post ID's in the database and creating a custom 404 error page redirect. A solution is being sought after, but no promises.
Ok, this is done. All old threads that reference other old threads with hyperlinks in the post body are now being redirected. This is an awesome, slick piece of work by a fine database programmer. Thanks so much!
If you happen to stumble upon an exception that doesn't work, please let me know.
Traders' Consortium