There are rebuilds and then there are fire sales, and what the Giants are doing with their deconstruction project is going to be hard to sell to the remaining players in their locker room.

This franchise in transition packed up massive defensive tackle Damon “Snacks” Harrison on Wednesday and shipped him to the Lions for a 2019 fifth-round draft pick. The trade comes a day after cornerback Eli Apple, the team’s first-round pick in 2016, was sent to the Saints for a 2019 fourth-rounder and a 2020 seventh-rounder.

Harrison, dubbed “Snacks” by former Jets coach Rex Ryan when Harrison was an undrafted player with the Jets, was part of the 2016 free-agent spending spree that refurbished a lousy defense. Former general manager Jerry Reese gave Harrison a five-year, $46.25 million contract, knowing full well Harrison was largely a one-dimensional player — a run stopper. He is dominant in that one dimension, though.

This trade will resonate more deeply with Harrison’s now-former teammates. Safety Landon Collins tweeted, “#Maaaaannn” and then, “#Brrrrrooooo” upon hearing the news. When Lions linebacker Devon Kennard, who spent the past four years with the Giants, tweeted, “Let’s go Snacks,” Collins responded with, “Bruh go to sleep.’’

Co-owner John Mara, at the owners’ meetings last week, said, “I’m not so sure it’s going to be quick fix.” A full and complete rebuild rarely is. The Giants are 4-19 in their last 23 regular-season games.

The new coaching regime did not seem to warm up to Harrison and this move has a different vibe than the one a day earlier for Apple, who was still playing on his rookie contract. Apple is 23; Harrison turns 30 on Nov. 29. Harrison was scheduled to count $7 million on the 2019 salary cap and $9.25 million on the 2020 cap. Looking ahead, it is clear general manager Dave Gettleman did not view that as money about to be well-spent. The Giants without Harrison will save $7 million on the 2019 cap and take on $3.2 million in “dead’’ money, according to Spotrac.

Coach Pat Shurmur, suddenly in the throes of a rebuild with nine games left to play, did not exactly wax poetic about the players he lost.

“We were presented with some deals,’’ he said. “We made a couple trades and we’re moving on.’’

The 2016 defense allowed the second-fewest points in the NFL, but only three players off that starting unit remain: Collins, Janoris Jenkins and Olivier Vernon. Only nine players on the entire roster remain from the team that faced the Packers in a wild-card game.

Trading Harrison is more about his cost, but other factors were considered. Harrison was popular in the locker room, but he groused about his frosty relationship with the media and more than once declared he is not a leader. Shurmur has said, repeatedly, that some of the best leaders on the team can be the youngest players, even rookies. The priority of this trade is certainly not acquiring assets, as all the Giants got back is a fifth-round pick. Consider this an addition by subtraction financial decision by the Giants.

Harrison is a 355-pound man-mountain and remains one of the NFL’s top interior defensive linemen, but this season he was getting on the field only about half the snaps. He played 30 snaps Monday night in a 23-20 loss to the Falcons. The Giants through seven games are allowing 113.9 rushing yards per game, a disappointing 20th in the league. Harrison is Pro Football Focus’ seventh-highest defensive lineman and fourth-best against the run. He is only 43rd in snaps among defensive linemen.

“I thought Snacks had some really good reps in the games,’’ Shurmur said, “and just like everybody else, there are things in each game that could’ve been better.’’

The Lions are 3-3 and ranked 30th in the NFL in run defense. This trade not only makes sense for them, it is a steal.

The Giants do believe they have some promising young defensive tackles. Rookie B.J. Hill was a Day 1 starter, as was Dalvin Tomlinson, the 2017 second-round pick. R.J. McIntosh, a 2018 fifth-round pick, is working his way back after coming off injured reserve and should be able to play sometime after the bye week.

In the short term, this unquestionably hurts the Giants’ defense, as Harrison’s rare ability to take on double teams, cause disruption up front and often make the tackle are traits that cannot be duplicated by anyone on the roster. When a team loses six of its first seven games and is in a downward spiral, radical changes are in order. Add this one to the list.