This is an NOS choke tube, Ford part # B6A 9890-A.  This choke tube was used on 1956 and 1957 Thunderbirds; 1956 thru 1958 Mercurys with a Y block 312 and 1956 thru 1959 Ford passenger cars with a factory Y block V8 engine.  NOTE: It was NOT used on the 1956 or 1957 Ford, Thunderbird  or Mercurys with  the factory optional dual quad intake manifold.  The tube measurers 7.62” in length. This tube is often rotted thru which allows dirt and carbon to damage the choke assembly.   See my eBay store for the par of 1956 an 1957 factory dual quad choke tubes and the ’57 NOS choke tube end deflector and the ‘57 choke tube to choke assembly. Thanks!