Edelbrock Performer RPM Air-Gap manifold fits SB-Chevy 265-400 CID 1955-86. No factory box. Dual plane design, 4 bbl square bore flange non-EGR operating rpm range 1500-6500, intake manifold height 4.720in. Port exit dimension 1.14″X 1.95″. Not for 1987 and later cast iron heads or L98 cylinder heads. Will not fit under stock corvette hood. Please e-mail with questions