The eligibility criteria for admission to a 3-year LLB course may vary depending on the institution and the university offering the course. In general, most institutions require candidates to have completed a Bachelor's degree from a recognized university with a minimum percentage of marks. As you have completed two post-graduate degrees from the University of Madras and are 63 years old, you may be eligible to apply for admission to a 3-year LLB course, but this may depend on the specific admission policies of the institution and the university offering the course. It is recommended that you check the specific eligibility criteria of the institution and the university offering the course to confirm your eligibility. Additionally, some institutions may require you to appear for a Common Law Admission Test (CLAT) or other entrance exams conducted at the state or national level to be considered for admission. It is recommended that you check the admission policies and procedures of the institution and the university offering the 3-year LLB course you are interested in and contact them directly to inquire about their specific admission requirements. This will ensure that you have accurate and up-to-date information and can make an informed decision about your eligibility and the admission process for the course.