BAK Industries 162121 Features: Intermittent Locking Positions Drive Fully Open Or In Intermittent Positions Will Not Leak And Is Outstanding In Snow And Ice Scuff/Scratch And Ding Resistant Removes In Seconds Allows Full Access To Stake Pockets Works w/5th Wheels/Bedliners/Bed Extenders Lock Tailgate For Absolute Security Height: 8.00 Width: 23.00 Length: 68.00 Fitment: 2017/GMC/Sierra 3500 HD/SLT Extended Cab Pickup 4-Door/6.6L 6599CC 403Cu. In. V8 DIESEL OHV Turbocharged::Bed Length = 78.8, Bed Side = Fleetside, Dually Bed^^2017/GMC/Sierra 3500 HD/SLT Extended Cab Pickup 4-Door/6.0L 5967CC 364Cu. In. V8 GAS OHV Naturally Aspirated::Bed Length = 78.8, Bed Side = Fleetside, Dually Bed^^2017/GMC/Sierra 3500 HD/SLT Extended Cab Pickup 4-Door/6.0L 5967CC 364Cu. In. V8 FLEX OHV Naturally Aspirated::Bed Length = 78.8, Bed Side = Fleetside, Duall...