ARP High Performance Series Main Stud Kit - Ford 351W w/o Windage Tray 33005BK Double flares 3/16"

Double flares 3/16"

but for a more precise measurement a caliper should be used

Ford Mustang 1983-97

Aeromotive Diesel Universal Lift Pump

ARP High Performance Series Main Stud Kit - Ford 351W w/o Windage Tray 33005BK Double flares 3/16"ARP High Performance Series Main Studs eliminate main cap walk and protect the treads in cylinder block. ARPs product line contains thousands of part numbers, and has expanded to include virtually every fastener found in an engine and driveline. These range from quality high performance OEM replacement parts to exotic specialty hardware for Formula 1, IndyCar, IMSA, NASCAR and NHRA drag racing and marine applications. Since 1968, ARP is the fastener