If a crack is displayed on the glass of the VAZ-2108/09/99 headlamp (e.g. at impact with a stone), there is no need to change the entire unit. The point is that the glass on the headlamps of this model is replaceable and is attached to the shell on latches and sealants. You need to buy glass (part number 351.3711201 left and 35.3711201 right), gently lift the broken glass, clean the old seal with a knife, and make a new glass. The cost of the non-original glass is 100 rubles.
