Will probate or not

My father who had two sons wrote a Will and registered in Sub-registers office in the name of his one son ONLY and passed away in Jan 2010. The property is in outskirts of Chennai and in Jul 2011 came under the jurisdiction of Chennai. The son who is the Will heir now wants to sell the property and has finalised a buyer to find the Will needs to be "Probate". The other son who didn't receive the Will inheritance does not want to sign "No Objection". The buyer wants the property in one month. Can we get the name changed in Chennai Corporation office with the Will copy, or do we need to Probate the Will. If so, how long is the "Probate" process when there is an objection. Thanks for your valuable suggestions.