Elevation: 7,421 ft
This peak is not in the book.
Jack Benchmark is a remote summit located southwest of Reynolds (a town that no longer exists). The peak’s closest neighbor is Rooster Comb Peak which is located rough 2.0 miles northeast of Jack Benchmark, These two mountains and Whiskey Mountain sit in an area of mixed BLM, State of Idaho and private lands. Access to this interesting area is found on pages 345-346 in Idaho A Climbing Guide [(A)(1)].
Brett Sergenian is the only person I know who has visited the peak. His trip report is linked below. USGS De Lamar