The ABS in my 74 looks to be in fine shape, but being as I have the interior just about completely removed, now would be the time to replace the entire ABS system with new ABS, or even PVC. I have had a few people tell me about ABS glue joint failures in their old house plumbing. I'd like to know what others have done in this situation. I have plenty of work to do such as replaceing the copper water lines, so I don't want to replace the ABS for no reason.
Thanks for the imput.