As per the provisions of the Payment of Gratuity Act, an employee is entitled to gratuity once he completes 5 years of continuous service with an employer. Such gratuity is payable within 30 days of resignation, retirement, or death (to legal heirs) of an employee.
The Madras High Court, in a judgment reported in 1998 LLR 1072, has held that if an employee has completed 240 days in the 5th year of service, he shall be deemed to have been continued in service for one year as stipulated by Section 2A of the Payment of Gratuity Act, 1972, and hence he is entitled to gratuity.
From the details given by you, you have joined the services on 2nd May 1999, and resigned on 30th April 2003. Therefore, you are entitled to claim gratuity from your ex-employers. Along with this, since the employer has failed to pay gratuity within 30 days from the date of your separation, you shall also be entitled to claim interest upon the same from the date of your separation until the actual payment of gratuity.
If your ex-employer does not pay the same, you can just file an application to the Labour Commissioner in your area about the same, and then he would initiate proceedings against your ex-employer.
I hope this resolves your query.