-263xhd transfer case. -Specs: 29 input splines 31 output splines -Fits vehicles listed 2001-2007: 6.6 Diesel Duramax, 8:1 gas engine Chevy Silverado diesel 2500HD-3500 GMC Sierra diesel 2500HD-3500 -Bolts up to Allison Transmissions and ZF6 manuals -Has all new bearings, Updated case saver. New heavy Duty rear Aluminum case. Has heavy Duty 1 1/2 chain and gears, new friction, new pump update, all new seals. Units been test shifted for quality control and check for leaks. No unit leaves until it passes quality control -No upfront core cost. Free return label! Must receive core in crate shipped within 10 business days to validate warranty. Please contact us to verify this is your correct unit before ordering 4436406100 If the core and crate are not received there will be a 300 crate and core charge, and no warranty! Comes with a 1-year unlimited mileage warranty -No shipping outside lower 48 states $125 will be charged to all lower 48 states. -Built by a professional mechanic with over 25 years of building experience -message me if need to confirm exact fit. units do not come with encoder motor or speed sensor - Warranty does not cover broken teeth or broken gears or broken cases due to heavy towing, lack of oil or abuse and u-joint issues not addressed -NO WARRANTY if we don't receive the crate and core, core MUST be same unit as we sold you, NO EXCEPTIONS - I do expect you to send the same unit as a core as I sold you and return my personal property! my shipping crate - returns are accepted, I do not refund the cost of shipping on customer mistake ordering wrong units, restocking fees apply also no refund on installed units. not a diagnostic tool! - after your purchase I will message you with contact number to call, so we go over the details make sure this is your correct unit and shipping details Please call will speed up shipping. Domestic Transfer Case Services - PLEASE LOOK AT YOUR IDENTIFY TAG FOR AN EXACT FIT!!!