Finding John Gilleland

Am hoping to network with those researching the Gilleland/Gilliland name.  I have a John Gilleland buried in Decatur Coiunty Indiana about 1834.  Marker says 5th PA Regiment Rev War and thats about all I know.  I do know he originally came into Indiana and settled in Union Couinty, then moved to Decatur County.  Buried adjacent to him is my 5th Great Grandfather John Gilliland. He was in the War of 1812.so most likely is to young to be old Johns son.  I do know young John married Susanah Harris in North Carolina, and some have suggested that a Robert Gilliland/Betsy Stewart are the parents of young John but even if that is so, it's never been determined how Robert and old John are related.  I know this is a brickwall for many researching the family, so thought I'd try something different by posting here to see if I can get any nibbles.  Any information, comments, or suggestions woiuld be appreciated.  Thank you.