The Light Blues captain has had a difficult time of late, with his mistake against Falkirk encapsulating a period of poor form for the centre-back, who was also sent-off against Hearts the last time the teams met.
Johnstone has suggested that a centre-back pairing of Darren McGregor and Marius Zaliukas would be a more solid partnership whilst McCulloch is capable of having a greater impact at the other end of the pitch.
Talking about the struggling captain, Johnstone explained he understands the fans’ frustrations with the player, but using his physical presence up front during the play-offs could guide Rangers back to the Scottish Premiership.
"When the manager put Lee up front late on when things were getting desperate he actually looked good,” he said.
"I can understand why fans are frustrated, but they have to keep that under control in the closing stages of the season."
He continued: "Lee has shown that if the team are going to put balls into the penalty area, he has still got that jump he needs to get on the end of them. Maybe he will find himself a place up front rather than at the back."
McCulloch does have experience playing as a striker for both Scotland and Rangers, and was the Gers’ top goal scorer in the 2012-13 season, netting 23 goals in all competitions when Rangers played their league football in the third division.
The 36-year-old is out of contract at the end of the season and is playing for his future at the moment, but a successful change in position could go some way to showing whoever is making the decisions at Ibrox next season that he’s capable of playing for one more season.