Job change on I-140 approval with 1 year extension in 6th year

[tj456]

I am in 6th year of my H1B and got extension for 1 year based on I-140 approval. I am planning to switch job.

Can the Current I-140 approved doc be valid to get extension for 3 years with New employer(or) Will I get only one year

extension with New employer. If 1 year, what if PERM is not filed/not approved within the timeframe(1 yr).

Please share your thoughts and suggestions.