Service tax on contrct manufacturing

Dear ca clubians,

i request ur goodself to provide me the clarification on this query,iam posting this for the 4th time.

 I would like to know the st liability on work contract, where the activity involves the supply of labour and material. our activity is fabrication of bus body on the chassis supplied by the customer, where in cutomer also supplies some material. i heard that manufacturing activity doesn't attract st.  i would like to know the st liability in respect of NEGATIVE LIST  announced in the budget