GM Original Equipment Automatic Transmission Oil Cooler End Fittings are used in the transmission cooler circuit to connect components and lines. Allison 1000 Transmission Cooler Line Fitting, Fits Model Year 2001-2002 Duramax This fitting is for early style housing 3/4 thread with early style lines.This original equipment transmission oil cooler end fitting is manufactured to fit your specific GM vehicle and will provide the same performance, durability, and service life of your factory original equipment.