Boss 351 Cylinder Block; 2.749 Inch Main Journal Diameter; 4.125 Inch Bore Capacity/ Finished At 3.990 Inch To 3.995 Inch Rough Bore; 9.2 Inch Deck Height; 2 Bolt Main Caps On Journals 1 And 5 And Splayed 4 Bolt Main Caps On Journals 2/ 3/ 4; Not For Sale On Pollution Control Vehicles