Remove your purge valve and cap off the port- Or use it to plumb a boost gage for turbo applications. This fits all truck LS manifolds with purge solenoids. To use as a block-off just bolt it in using the stock hardware. To use for a boost gage, drill through with 1/8” bit (the part is already drilled within 1/16” of breaking through), and thread in your 1/8” npt sender or adapter.
To use this without the stock shoulder bolt and rubber boot, use an m6 bolt and place a washer underneath the part.