Transmission fittings are designed to replace OEM adapters in '97 and later 4L80E transmissions. These will allow you to use -6AN hoses and fittings
6AN 70 Transmission Cooler Hose Kit Lines Fitting Kit
Aeroflow Transmission Cooler Fittings 1/4″ NPSM Thread To, 47% OFF
For GM 4L60E 4L80E Flexible SS Braided Transmission Cooler Lines
4L80E 1-2 & 2-3 Shift Solenoid - Rostra 52-0356 - WARR Performance LLC
ROOSAIN 6AN x 1/4NPSM 4L80E GM Transmission Oil Cooler
Transmission Fittings Archives - WARR Performance LLC
Transmission Archives - WARR Performance LLC
NEW Transmission Oil Cooler Adapter Fittings 6AN to 1/4NPS FOR GM
Russell Performance 640331 -6 AN to 1/2-20 Inverted Flare Fitting
Bowler Transmission Front & Rear Cooler Fitting (-6AN Male 9/16-18
CPP 4L80 Transmission Cooler Line Adapter Fittings. For use with 4L80 transmissions. Includes both long and short fittings specific for the 4L80. This
1997-08 4L80 4L80E Transmission Cooler Line Fittings Kit -6AN 6AN 6 AN x 9/16-18