 The final drive chain is moved to the right side and it is the most obvious change from the old model apart from the new engine.In October 2012, Royal Enfield launched the new 350 cc and 500 cc variants of the Thunderbird with a facelift.It features front and rear disc brakes, a teardrop shaped fuel tank, a split seat, digital speedometer console and fuel gauge, projector headlamps, LED tail lights and various cosmetic improvements over the 350 cc.