AP02 NP261HD Transfer Case Unit For 2001-2007 6.0L | -/ 2500/3500 HD 12581007 Transfer case unit designed for 2001-2007 3/4 and 1 ton applications with floor shift configuration.Intended for GM trucks equipped with RPO code NP2 and 6.0L engines.Features a 32 spline input shaft compatible with the 4L80 transmission.Front output has 32 internal splines with one tooth missing.Rear output has 32 external splines.Requires gear oil type 75W-90.OE numbers include 261HD, 412-541, RTC261GHD, 112581007, 12576436, 12576437, 12579911, 12579912, 12579913, 12581006, 12576435, 12581008, 12588518, 12588519, 12588520, 15023640, 15039437, 15045471, 15046965, 15046966, 15709254, 15709260, 15753788, 15753789, 24228405, 24220410, 24220425. Fits models including Silverado 2500 HD 2001-2007, Silverado 3500 2007, Sierra 2500 HD 2001-2007, and Sierra 3500 2007.Verify fitment by comparing your existing unit with provided photos and OE numbers. Compatibility Statement: This is not an manufacturer part.Brand/model references are used for fitment guidance.