I believe it was 1978.
Minnesota Vikings Mick Tingelhoff THE BLITZ..AND THE BLOCK 14x17 Calendar Poster
Mick Tingelhoff Autographed Purple Pro Style Jersey W/ HOF - Beckett H – The Jersey Source
Mick Tingelhoff passes away - Daily Norseman
Gallery: Mick Tingelhoff joins NFL Hall of Fame
Vikings' Tingelhoff Elected To Pro Football Hall Of Fame
Greatest Viking Of All Time Tournament: Mick Tingelhoff Advances - Daily Norseman
Vikings Corner: A Granddaughter's Long-Awaited Hall of Fame Smile
Image Gallery of Mick Tingelhoff
Mick Tingelhoff this year's Seniors nominee to Hall of Fame - NBC Sports
Mick Tingelhoff: 17 years, 240 straight starts
Mick Tingelhoff made last-minute call to hand off Hall of Fame speech – Twin Cities
Mick Tingelhoff, 81, Vikings Hall of Fame Center, Dies at 81 - The New York Times
Signed Mick Tingelhoff Photograph - 8X10