Ask your seller first...he should be able to provide you some information.
Second, with the board serial number you could probably ask Hans at Kessler some more info.
And may be something else to consider........even if you seem to be into the right range for the board lenght, 162 is the SL race size in Kessler's line, and (guys correct me if i'm wrong), probably quite stiffer than the 168 or even the 170 despite a more GS size !!!
Assuming that we speak about stock boards and that your riding technic is ok (No offense at all).
And what @Corey wrote just before is also really right on point.
A shorter board doesn't always means a softer board.