It seems as though the 737 operating the morning STN-TXL varies, it will either be the 4, 7 or 800. The STN-DTM route (along with STN-PAD and STN-MGL) is always served by a BAe 146, with the morning DTM service (8941) operating onwards to VIE.
Before you ask, I think it may be the 146-300, and in addition we are expecting the Palma (PMI) route to be launched this winter.