The Holley 4150G, 4150MG and 4150EG were governed versions of the Holley 4150 4 barrel. These were built from 1957 to about 1991. 4150G and 4150EG carbs have a governor diaphragm on the passenger side of the carburetor. The EG version has a governor bleed solenoid valve and is used with an electronic governor system. The 4150MG, used mostly on Ford SD 477 and 534 motors does not use a governor diaphragm on the carb.
Carburetor numbers are stamped on the front of the choke tower, except on some Ford SD models where the number is on the back of the choke tower.