As of version 4.2, each slice line in the PAR file contains gradient b-value and direction information. The PAR files can be opened in Note pad (easiest to open Notepad and drag the PAR file into the Window). In the snapshot below, the diffusion direction is the second-to-last parameter in the line, so 0 0 -1 for the first slice of the first volume. (Note that the line often wraps around onto 2 lines as below, or in some cases even 3 lines). The b value is for parameters prior; it's easy to spot because it's the only repeating high integer (e.g., 800, 1000).
