Here's an odd ball question. As the title says, I need a long LH thread 3/8-16 tap. I can't find one. I tried modifying an existing tap by welding an extension (TIG, MIG, various cooling techniques), but it didn't work as the weld site was always too brittle. I don't have the capacity to anneal and harden (properly) and I can't chuck the item in a lathe. Any ideas to solve this problem?