Mdrol is probably the best clone of SD, it's pretty legit (aside from the bunk batches a while back).
If you are running 20mg, I'd use a SERM. I've run a few 10mg 3 week cycles with OTC -- a mix of AI PCS, 6OXO, I3C, Trib and some other junk over the years. These days the best bet for OTC is some form of Trans Resveratrol, I3C and some other test booster IMHO.
Disclaimer: Having a SERM on hand is probably a good idea while dealing with SD.