Couldn't find a list of former Eastern Conference D of the year, but I found a list of WHL D of the years...
Top Defenceman Winners
2011-12 Alex Petrovic, Red Deer
2010-11 Stefan Elliott, Saskatoon
2009-10 Tyson Barrie, Kelowna
2008-09 Jonathon Blum, Vancouver*
2007-08 Karl Alzner, Calgary*
2006-07 Kris Russell, Medicine Hat*
2005-06 Kris Russell, Medicine Hat
2004-05 Dion Phaneuf, Red Deer
2003-04 Dion Phaneuf, Red Deer
2002-03 Jeff Woywitka, Red Deer
2001-02 Dan Hamhuis, Prince George*
2000-01 Christian Chartier, Prince George
1999-00 Micki DuPont, Kamloops
1998-99 Brad Stuart, Calgary *
1997-98 Michal Rozsival, Swift Current
1996-97 Chris Phillips, Lethbridge
1995-96 Nolan Baumgartner, Kamloops*
1994-95 Nolan Baumgartner, Kamloops*
1993-94 Brendan Witt, Seattle
1992-93 Jason Smith, Regina
1991-92 Richard Matvichuk, Saskatoon
1990-91 Darryl Sydor, Kamloops
1989-90 Kevin Haller, Regina
1988-89 Dan Lambert, Swift Current
1987-88 Greg Hawgood, Kamloops*
1986-87 W Glen Wesley, Portland
E Wayne McBean, Medicine Hat
1985-86 W Glen Wesley, Portland
E Emanuel Viveiros, P.A.
1984-85 Wendel Clark, Saskatoon
1983-84 Bob Rouse, Lethbridge
1982-83 Gary Leeman, Regina
1981-82 Gary Nylund, Portland
1980-81 Jim Benning, Portland
1979-80 Dave Babych, Portland
1978-79 Keith Brown, Portland
1977-78 Brad McCrimmon, Brandon
1976-77 Barry Beck, New Westminster
1975-76 Kevin McCarthy, Winnipeg
1974-75 Rick Lapointe, Victoria
1973-74 Pat Price, Saskatoon
1972-73 George Pesut, Saskatoon
1971-72 Jim Watson, Calgary
1970-71 Ron Jones, Edmonton
1969-70 Jim Hargreaves, Winnipeg
1968-69 Dale Hoganson, Estevan
1967-68 Gerry Hart, Flin Flon
1966-67 Barry Gibbs, Estevan