So I am in need of these(they aren't as "hard" as oxy(schedule lower iirc) and they help my severe back pain). I have been told they are prevent in clearnet Indian Pharmacies but I have had no luck in India or Canada. I understand codeine is schedule IV so I can't imagine it should be too hard to find. I found a vendor on Alphabay named MDMA4USA but it seemed like a potential scam and I don't trust ABs feedback system. Apparently tramadol is similar and I already utilize Kratom as much as I can in my pain management toolkit.
Try UK vendors, codeine and dihydrocodeine is very easy to get here. Terrysukstock and stealthpharmacy off the top of my head are good, lots of options tho