I served in military from1968 - 1975 two years active. When I filed for Social security. Was I suppose to get extra because I served during that time on active duty & can I still file if eligible??????
What you would get are deemed military wages (DMW) for the periods that you served on active duty (https://www.ssa.gov/OP_Home/handbook/handbook.09/handbook-0953.html). DMWs are extra wages that are added to your actual military wages for periods of active duty, and they generally amount to $100 per month or $300 per calendar quarter.
So, say you were on active duty for the entire year of 1971 for example, and you were paid $2000. Including DMWs, Social Security would credit you with wages of $3200 for that year (i.e. $2000 actual wages plus $1200 deemed wages), which could then be used in the calculation of your benefit rate.
DMWs have been automatically added to the earnings records of military personnel by Social Security starting with 1968. Therefore, it sounds like you are almost certainly already receiving all of the extra credits to which you're entitled from Social Security.