After doing some comparisons (specs, parts, and high rez pictures), the Street Twin and the Street Scrambler are the closest. The Bonneville bikes T100 and T120 are different (exhaust and brakes for sure). An easy mash up would be adding the wheels, rear shocks, and forks from the Street Scrambler to the Street Twin. The frame of the Street Scrambler is different from the Street Twin in the rear where room has to be made to accommodate the high exhaust. The Street Twin exhaust has many parts and does not fit a T100/ T120. It doesn't look like the tanks from the Street Twin and the T100 are interchangeable either.