fyi......Has nothing to do with 4x4, the body style and length of box is what is the controlling factor
Accessory Name
Splash Guards - Rear Molded
Help protect your Sierra from tire splash and mud with these Molded Splash Guards that fit directly behind your rear wheels. Available in textured black, as well as select body colors.
Part Number
MSRP (USD)
Molded Rear Set, For Use on 3500 HD Models without 9,900 GVWR (SRW) or 2500 HD Models with Dual Rear Wheels (R05), Not For Use in Texas, Red GMC Logo, Black
19212556
$ 90.00
Molded Rear Set, For Use on 5'8" Short Box, Black (41U)
19170474
$ 85.00
Molded Rear Set, For Use on 5'8" Short Box, Blue (37U)
19212568
$ 85.00
Molded Rear Set, For Use on 5'8" Short Box, Labyrinth (GGW)
19212570
$ 85.00
Molded Rear Set, For Use on 5'8" Short Box, Red (74U)
19170478
$ 85.00
Molded Rear Set, For Use on 5'8" Short Box, Red GMC Logo, Black
19212554
$ 50.00
Molded Rear Set, For Use on 5'8" Short Box, Silver (GGZ)
19212569
$ 85.00
Molded Rear Set, For Use on 5'8" Short Box, Stealth Gray (46U)
19170475
$ 85.00
Molded Rear Set, For Use on 5'8" Short Box, White (50U)
19170476
$ 85.00
Molded Rear Set, For Use on 6'6" Standard Box or 8' Long Box, Black (41U)
19170481
$ 85.00
Molded Rear Set, For Use on 6'6" Standard Box or 8' Long Box, Blue (37U)
19212572
$ 85.00
Molded Rear Set, For Use on 6'6" Standard Box or 8' Long Box, Labyrinth (GGW)
19212574
$ 85.00
Molded Rear Set, For Use on 6'6" Standard Box or 8' Long Box, Red (74U)
19170485
$ 85.00
Molded Rear Set, For Use on 6'6" Standard Box or 8' Long Box, Red GMC Logo, Black
19212553
$ 50.00
Molded Rear Set, For Use on 6'6" Standard Box or 8' Long Box, Silver (GGZ)
19212573
$ 85.00
Molded Rear Set, For Use on 6'6" Standard Box or 8' Long Box, Stealth Gray (46U)
19170482
$ 85.00
Molded Rear Set, For Use on 6'6" Standard Box or 8' Long Box, White (50U)
19170483
$ 85.00
 
** MSRP. Excluding installation, taxes and wheel components (if applicable).