This for the 77-79 Pontiac Trans Am with the OLDS 403 V8 ..its the underside of the fibreglass shaker.

It clamps onto the top ring of the specific air filter housing.  You would buy this if replacing the lid ..OR changing from another engine brand back to a 403 Olds..

The Olds shaker base has suttle differences to other base plate.. offset is different to Pontiac 301 or 400V8 pr  Chev SB in this shaker base plate due to offsets and extended depths of underside wall support that positions the fibreglass shaker to a central position.. so you can ..

• 1: close the hood properly
• 2: not have the shaker offset or too low.

This is for a OLDSMOBILE 403 V8..  is  right for the 77-79 Trans Am with a 403 Olds engine in it.