Kevin Judge disappeared from Lupset in April 2013 and his family are renewing their calls for help to discover what happened to him.
Lisa Judge, one of Kevin’s daughters, said life had been "horrendous" since she last saw her dad.
She said: “Since dad's disappearance life has been a real struggle. I loved my dad very much am tormented by thoughts of where he can be and what has happened to him, whether he is still alive or dead.
“There is no closure to this and there never will be until he is found. I believe that someone out there may know something or at least have an inkling as to where he might be.
“I urge anyone out there to come forward as any piece of information, no matter how trivial it might sound, may lead to my dad's whereabouts. Me and my family need closure to this nightmare.”
Wakefield District Police never closed the investigation and continue to try and trace Kevin, remaining in touch with his family over the years which have followed.
Kevin, known as “Judgey” to his friends would now be 74 years of age. He was last seen on Monday, April 15, 2013 at 12.30pm near to his home address on Esther Avenue, Lupset, where he was dropped off by taxi, having been in Wakefield city centre that morning.
Lisa Judge visited her dad early the following morning to discover him missing.
There were no signs of a disturbance at the house and Kevin’s distinctive trilby hat, which he always wore, was still at his home address.
Extensive enquiries were subsequently carried out to find Kevin by Wakefield CID and the Wakefield Police Safeguarding unit
The police gained some CCTV from Wakefield city centre showing Kevin’s movements on the morning of April 15, 2013. The police still remain in need of vital pieces of information that would indicate what happened to Kevin once he arrived back at his home address that date.
DI Jordan Piper of the Wakefield District Police Safeguarding Unit, said: "The investigation into Kevin’s disappearance has never been closed and will not be until he is found.
“The past six years have been very hard for Lisa and her family as Kevin’s disappearance has obviously left them troubled and upset.
“We continue to work together with other agencies to try and find Kevin."
Viv Segerius-Allick of the Wakefield District Police Safeguarding Unit, said: “We remain determined to do all we can to help them find some answers and I would ask anyone who has any sliver of information, however vague, who may not have come forwards to now do so.
“Anyone who can assist with information is asked to contact the Wakefield District Safeguarding Unit on 101 referencing the case.
“Information can also be given online via www.westyorkshire.police.uk/101livechat