I realize you are going to USA-India, and I only know about USA-Europe.

I take extra luggage Italy-USA at a rate of about $75 per 32kg unit. Maximum dimension is 63". The dimension limit is not enforced. I haul 3-5 of these at a time, frequently. It is much less expensive than UPS/DHL/ commercial airfreight, and even less than ocean freight. The rate is governed by an agreement of some sort.

I would recommend that you spend a lot of time checking the rate on the airline you are traveling. If you cannot get answers over the phone, go to the airport and talk to the people who look up the rate. They are at a separate desk, usually not at the check-in counter.

This is not overweight luggage, but more checked luggage. Do not exceed the max allowed weight for each package.