The visitors took an early lead when some statuesque Grimsby defending allowed Drewe Broughton to head Matthew Saunders' deep free-kick back across goal and Chris Herd diverted the ball home from close range.
But the Mariners grabbed a deserved equaliser seven minutes before half-time, Lee Peacock claiming the vital touch on the line after an almighty scramble caused when Lincoln failed to clear a Jamie Devitt free-kick.
Peacock scored a second within 49 seconds of the restart when he got a second bite at Michael Coulson's right-wing cross from 10 yards.
But Grimsby couldn't hold on for a priceless victory and Gilmour levelled, albeit at the second attempt, after Rob Atkinson had been penalised for a tug in the penalty area.
Source: Team Talk
Source: Team Talk