Questions? Call Us:631-982-0042
M-F 8AM-4PM ET
Choose your trim in My Garage to confirm exact fit.
Exact-fit parts for the 2021 GMC Sierra 3500 HD AT4.
Go Rhino
Part # D6410000T
$179.99
Westin
Part # 56-24135
$703.99
Truxedo
Part # 1705211
$165.99
WeatherTech
Part # 120122
$138.95
Go Rhino
Part # 20404887T
$1399.99
Westin
Part # 21-534775
$1042.99
Go Rhino
Part # 960001T
$484.99
Cognito
Part # 110-91295
$143.31
Putco
Part # 529005
$84.99
Westin
Part # 20-44135
$624.99
Pace Edwards
Part # M-BLCA34A65
$2886.23
Dee Zee
Part # DZ95250TB
$488.15
Dee Zee
Part # DZ284123M
$237.32
Dee Zee
Part # DZ95002
$55.97
Putco
Part # 402671
$156.99
Westin
Part # 21-24130
$356.03
Pace Edwards
Part # BLCA34A65
$2886.23
Dee Zee
Part # DZ95054RTB
$464.82
Pace Edwards
Part # KMCA34A65
$2329.10
GEN-Y Hitch
Part # GH-25107
$129.95
This page groups parts listed for the 2021 GMC Sierra 3500 HD AT4. Some products fit every trim, while others depend on submodel, engine, drivetrain, or brake package. Use your trim in My Garage or the product page fitment check to confirm exact fit.
We offer a wide selection of exterior accessories parts for the 2021 GMC Sierra 3500 HD AT4. This page narrows the catalog to the year, make, and model; use your trim on product pages to confirm exact fit when a part only fits certain submodels.
We carry parts from trusted brands including Go Rhino, Westin, Access, Dee Zee, and Putco, plus many more. Filter by brand to find your preferred manufacturer.
Most in-stock items ship within 1-2 business days. Shipping rates are calculated at checkout based on your location.
Warranty coverage varies by manufacturer but typically ranges from 1 year to lifetime. Each product page includes specific warranty information from the manufacturer.
