SAE J532_201303 Standard includes dimensional specifications for those types of SAE filler and drain plugs having straight threads as follows
FIGURE 1 - RECOMMENDED HOLE DATA
FIGURE 2 - HEXAGON OUTSIDE HEAD PLUG (4201 09A)
FIGURE 3 - SQUARE HEAD PLUG (4201 09B)
FIGURE 4 - HEXAGON INSIDE HEAD PLUG (4201 09C)
FIGURE 5 - DETAIL X ENLARGED
FIGURE 6 - SQUARE SOCKET HEAD PLUGS
FIGURE 6A UPSET 420109D
FIGURE 6B BROACHED 420109E
FIGURE 6C CAST 420109F
FIGURE 7 - HEXAGON SOCKET HEAD PLUGS
FIGURE 7A UPSET 420109G
FIGURE 7B BROACHED 420109H
FIGURE 7C CAST 420109J