The Red Rebels have proven to be a tough opponent for the Ammies this festive period, following their 3-2 win on Boxing Day.
But this one looked like heading the home side`s way as they took a 15th minute lead through Anthony Dudley.
And although Craig Lindfield took the visitors into half-time all-square with a 36th minute equaliser, Salford re-took the lead 4 minutes into the second half through Jack Redshaw.
They held that lead until 3 minutes from time when Zac Corbett popped up with FC United`s equaliser.
Second-placed Harrogate Town kicked-off 2018 with a win as lowly Darlington FC were beaten 3-0 at the CNG Stadium.
Jack Emmett opened the scoring 3 minutes after the break with a well-taken finish, before Jordan Thewlis cut inside and found the bottom corner 6 minutes later to make it 2-0.
Joe Leesley added Town's third goal with almost the last kick of the game as the winger slalomed into the penalty area and found the top corner.
Defeat leaves the Quakers just two placed and two points above the drop zone.
Brackley Town have had a disappointing festive period and were held to a draw for the second time by neighbours Leamington, this time at St James`s Park.
Stefan Moore gave the Brakes the lead 2 minutes before half-time.
The home side eventually pulled back on level terms with 12 minutes remaining when Aaron Williams converted a penalty given for handball.
Spennymoor Town are fourth after achieving a holiday double over north-east rivals Blyth Spartans, who dropped to sixth.
The Moors won 3-2 on Boxing Day at Croft Park, and did even better in the return at the Brewery Field, running out 3-1 winners.
And that after coming back from being a 15th minute Dale Hopson goal down.
Kallum Griffiths immediately pulled the home side back on terms after 36 minutes.
Immediately after half-time, Rob Ramshaw gave the hosts the lead and Glen Taylor added a third with 69 minutes gone on the clock.
Spenymoor moved above Bradford Park Avenue into fourth after the Yorkshire side were held to a 1-1 draw at the Tameside Stadium by Curzon Ashton.
After winning at home on Boxing Day, Avenue were looking to complete a festive double when they crossed the Pennines to Ashton.
And it was looking good as they broke the deadlock through Oli Johnson just past the hour-mark.
But Curzon netted a last-gasp equaliser 4 minutes into stoppage time with a Sam Madeley header from a corner.
Kidderminster Harriers hold the final play-off spot after overcoming a determined AFC Telford United side to win 2-0 at Aggborough.
The sides shared a 0-0 draw on Boxing Day, but Harriers took the lead 5 minutes before half-time through Andre Brown from close range.
And sub Andre Wright wrapped up derby success for the hosts in similar fashion in the 74th minute.
Stockport County are eighth, two points adrift of Kidderminster, after winning 3-1 at the Impact Arena against a now third-bottom Alfreton Town side.
The Reds were already trailing to an early 7th minute Chris Smalley volley when they had Craig Westcarr dismissed in the 34th minute, apparently for dissent.
Smalley added his and County`s second 5 minutes after half-time and an own goal by keeper Chris Elliott made it 3-0 with 16 minutes remaining.
Brendan Daniels was brought down in the box 4 minutes into stoppage time and he dusted himself down to net a consolation from the penalty spot, but it was a worryingly sixth home defeat in a row for John Eustace`s side.
York City kept their first clean sheet since September 9th and striker Jon Parkin scored two more goals as the Minstermen are ninth following a routine 2-0 victory against basement side North Ferriby United at Bootham Crescent.
Parkin, who celebrated his 36th birthday just a couple of days ago, took his tally for the season to date to 23 with goals in the 31st and 76th minutes.
The Villagers finished the game with ten-men after Jake Skelton was sent-off after 69 minutes.
Second-bottom Nuneaton Town failed to follow up Boxing Day`s hammering of Tamworth as the Lambs gained revenge with a 2-0 home success.
Tamworth broke the deadlock after 27 minutes when a swift break forward allowed Connor Taylor the opportunity to strike low across Dean Lyness.
And Boro they found themselves two behind just 5 minutes later when winger Callum Powell curled home from just inside the area.
Chorley`s top seven hopes have been hit by struggling Southport this holiday period, and Kevin Davies` side followed up their draw at Victory Park on Boxing Day by beating the Magpies 3-0 at the Merseyrail Community Stadium.
Port led through David Morgan`s goal after 20 minutes.
The Magpies threatened to level on more than one occasion, but 5 minutes from time, Nathan Sheron grabbed Port`s second to kill the game, Jack Sampson adding a third for good measure in stoppage time.
Boston United ended a decent holiday period with a point from a 1-1 derby draw at the Northolme against Gainsborough Trinity.
Having won the Boxing Day encounter at the Jakemans Stadium, the Pilgrims found themselves behind to a 10th minute Ashley Worsfold effort.
Reece Thompson, on loan from Guiseley AFC, grabbed the leveller for Boston with a header 4 minutes into the second half.
Trinity had skipper Nathan Jarman dismissed in the 57th minute, but managed to hold on for a point which leaves them two above the drop zone, while Boston are now six points clear of the bottom three.