Yes. Version 372 was the last version which supported set-car! and set-cdr! for regular cons cells, so Arc 3 was locked to that version. However, Arc 3.1 overcame this limitation by using pointer manipulation to mutate cons cells anyway. This would sometimes fail, but this Arc 3.1 bug has been fixed in Anarki and Arc/Nu.
The /install page on this forum still refers to Arc 3, so this version dependency is a frequent point of confusion.
