The DT shifters are Sunrace 8sp indexed, £14.99 new from fleabay. I quite like them, reminds me of my youth. I have STI shifters on 3 of my other bikes (8,9 and 10 speed) and DT on shifters on the tourer. They're pretty bulletproof and don't get damaged in an 'off'
Not sure whether to keep or sell the 105 7 speed.