The Mariners brought in Andy Taylor for the injured Danny North in attack, partnered by Gary Jones.
Ryan Bennett retained his place alongside Nick Fenton at the heart of the Town defence.
John McDermott, who was named in the starting line up, was playing his last game for the Mariners . . his 753rd aappearance.
The Mariners failed to spoil the party at Gay Meadow this afternoon but had a good go with a 2-2 draw, with a Nick Fenton equaliser on 94 minutes giving the visitors a share of the points.
It was a party atmosphere for what will now be Shrewsbury's penultimate game at the famous stadium.
The home side started as the manager had asked and were soon on the attack
Asamoah raced past Bennett before setting up Ashton on the lft but his cross was caught well by Barnes.
Andy Taylor almost got on the end of a probing pass by Boshell, and from a Town free-kick Fenton nearly got on the end of a Newey pass.
Bennett did well to keep up with Asamoah and force the ball out for a corner. The flag kick was played to the far post where Langmead's header went just wide.
Soon after Asamoah flashed a dangerous ball across the Town goal. Luckily for the Mariners there was no Shrews players able to get on the end of it.
In a rare Town attack, Taylor looked to use his pace but Langmead recovered well to keep the youngster at bay.
But the Mariners looked to spoil the party with their first real chance. Bolland's hopeful ball forward caught out the Shrewsbury defence as Taylor nipped in and rolled the ball goalwards. The ball trickled over the line - despite the best efforts of Hope to keep the ball out.
In added on time at the end of the first half, Asamoah broke away from the Town defence but was controversially pulled back for a foul on Tom Newey.
Half-Time: Shrewsbury Town 0 Grimsby Town 1
The Shrews showed their intent straight from the restart, as Cooke came inside from the left to fire a powerful shot just wide of Barnes' post. On 53 minutes Hope's near post header went just wide.
With the home side needing to win or draw to cement their place in the play-offs, they introduced Fortune-West to give them a three-pronged attack.
And Shrewsbury pulled level on 63 minutes from the penalty spot.
Cooke cross was controlled in the box by Davies who was adjudged to have been pushed by Toner as he looked to get a shot away.
Davies stepped up to send Barnes the wrong way and make it 1-1.
On 74 minutes the Shrews went ahead. Justin Whittle, who had replaced John McDermott a minute earlier, gave away a free-kick on the right. With everyone waiting for the kick to be taken, the ball was quickly whipped into the box where Langmead headed the ball down and into the net.
But the Mariners refused to lay down and Fenton saw a header from a Newey free-kick go just over the crossbar.
Burton replaced Asamoah for the Shrews as they looked to make sure of the victory.
And with just one minute of normal time remaining, Barnes made a fantastic one-handed save to deny Davies.
But in added on time, the Mariners decided to try to spoil the party again.A Town corner from the right was taken by Till and met by an unmarked Fenton to scoop the ball into the net.
The home side looked dejected but their play-off position was confirmed by the Shrews tannoy announcer.
