Let $A\in GL_d(\mathbb{Z})$ have finite order $n.$  Suppose that $k\in \mathbb{Z}$ is relatively prime to $n.$  Is $A^k$ conjugate to $A$ in $GL_d(\mathbb{Z})$?

For $d\leq 4$ the answer is yes.  Indeed the papers "On the finite subgroups of $GL(3,\mathbb{Z})$" by K. Tahara, 1971 and  "Conjugacy Classes of Torsion in $GL_n(\mathbb{Z})$", by Q. Yang, 2015 list all torsion elements up to conjugacy for the cases $d=2,3$ and $d=4$ respectively. There are not many cases that need to be checked, so I checked each case and the answer turns out to be "yes" in all of these cases. But I have no general argument for why things work out when $d\leq 4$, only computations.