The 10ft contours dataset, in a blockwide format, is too large in size to be made available as a shapefile (which has a 2GB size limit).

A dataset of all 10ft contours for the entire North_Susitna block is available in a geodatabase format here:
\LiDAR\North_Susitna\Contours\Geodatabase\North_Susitna_Contours.gdb

Individual tiles in shapefile format (with 2ft contours) are also available, here:
\LiDAR\North_Susitna\Contours\Shapefiles\By Tile