Depending on the year the older 350s were not drilled on the left side bosses especially the 2 bolt main car motors.some 307s 305s and even 327s didnt have threads on the l.f. boss. Every small block ive been around is drilled & tapped on the r.s. the upper hole being in line with the fuel pump push rod/bore...leave out the bolt, youve got an oil leak that looks like a front seal or timing case cover prob. put the wrong length bolt in instead, it binds the pump shaft and sheesa no run on her own
