Your grandfather was born and died too recent for any sources I have access to, but there are some researchers who browse this forum that might be able to build on this information from SSDI:
Long, Lowell E., b 28 Aug 1934; d 17 May 1996; last residence Alamo, Hidalgo Co, TX; SS card obtained in IL
TX Dth Idx 1964-1998 shows his middle name as Eugene and he not only resided in, but died in Hidalgo Co, TX. That's where is death would be recorded. You might obtain a copy of his DC, it should show the names of his parents, that is if the informant had that information.
I checked for some of the less common names of his sons on Switchboard.com -- http://www.switchboard.com/http://www.switchboard.com/ -- Click on Find a Person, enter Lowell Long, state of TX. There is one listed in Alamo, with address and phone number.