I was instructed to use two wood dowels and epoxy, slather the dowels to make sure they hold and a good coat between the two parts to be bonded. Don't over tighten or you won't have anything to bond. I was specifically told not to use glue in an end grain situation like this. I studied up on it and didn't want to undertake it but no one professional would and our members were too far away to mail it to. The other extensions I observed had a very minimum line, unlike mine.