maybe Galavision HD on 135W (both on C Band) I am yet to see audio being distributed in DD 5.1. Even PBS HD on Ku 125W uses DD 2.0 (although I think I have seen it 5.1 on some shows) which I find odd since I was expecting that those master signals were distributed with the highest posible quality (well some are distributed using DC II which I have no means to receive or are encrypted) but like I said DD 5.1 is extremely rare via FTA satellite. So you'd be better off via OTA.

All of PBS HD on AMC 21 is broadcast in Dolby AC3 5.1 along with NBC on AMC 1 & AMC 18 and other channels as well. However, your satellite receiver has to be connected to an A/V receiver that supports decoding AC3 audio in order to get surround sound. Also, not all shows being broadcast were actually recorded in 5.1 surround sound so that's why sometimes, you will only get DD 2.0 sound.