This is a new very high quality and very correct crank shaft pulley. This is a double groove for the Civilian jeeps that require a double belt. One belt is for the fan and generator and the other belt (which is thin) is for the Governor.  So that means one groove is for the wide belt and the other is for the more narrow belt.  The groves on this pulley are different sizes. This not the correct pulley for the M38 and M38A1 military jeeps. This is are very nice and heavier built pulley. The inside diameter on the rear measures about 3 7/8 inches. Please check if your timing cover has the dust shield on the front and measure it first. The pulley is supposed to fit over that shield. Some timing covers have them and some do not so this may not fit over that shield while installed. Please see pictures, thank you!  QTM Parts