Ford 351W OEM Style Main Cap Stud.
Stud (Into block): 1/2"-13 UNC 3.500" Long
Stud (Pickup Tube Flange): 3/8"-16 UNC
All Kevko stud mounted pickup tubes are based off this stud. If using a different mounting stud, the pickup tube may need to be modified to keep the proper pickup tube depth.