Chevrolet Silverado: Rust through at the rear cab corners and rocker panels (GMT800)
Rust through at the rear cab corners and rocker panels (GMT800) is a very common body & rust fault on the Chevrolet Silverado on the 1999–2006 cars, and we rate it major. Putting it right costs $800 to $4,500 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 14 documented faults on the Chevrolet Silverado.
- Vehicle
- Chevrolet Silverado
- Years
- 1999–2006
- System
- Body & Rust
What you are looking at
No photograph available
What goes wrong
GMT800 Silverados and Sierras rust through at the lower rear corners of the cab and along the rocker panels under the doors, often while the rest of the body looks tidy. The rockers have drain paths that block with dirt, and the rear tyre throws water and road grit straight at the area ahead of the rear wheel. US-import trucks from salt states can be well advanced before any bubbling shows, and filler or stick-on rocker covers are a common way of hiding it. Repair means cutting out and welding in repair panels, and rot that reaches the cab mounts or door pillar makes it far more expensive.
What you would notice
- Paint bubbles or holes at the bottom rear corners of the cab
- Crusty or soft metal along the rocker under the doors
- Rocker covers or fresh underseal on an otherwise old truck
- Water on the cab floor after rain
How to check it
Where to look. Lower rear cab corners behind the doors, rocker panels under the doors, extended and crew cab rear door sills
Open each door and look along the rocker sill and the bottom of the door frame with a phone torch for bubbling paint, rust holes or fresh filler.
Look at the lower rear corners of the cab, just behind the doors and ahead of the rear wheels, and press gently with a thumb: soft or crunchy metal is rust through.
Be suspicious of plastic or stainless rocker covers and thick fresh underseal, and ask what is under them.
Lift the floor mats and feel the carpet for damp.
If a workshop inspection is possible: on a hoist, have the inner rockers, cab mounts and cab floor checked from underneath, since outer panels are sometimes patched while the inner structure is rotten.
What it costs to put right
$800 to $4,500 at New Zealand independent workshop rates. That is for this job on its own, not for the car.
Ask the seller
- “Has any rust repair been done on the cab corners or rockers, and by whom?”
- “Why are rocker covers fitted?”
- “Was the truck imported from a salt-road region?”
Now check the Chevrolet Silverado you are actually looking at
Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.
Where this comes from
- GMSquareBody forum thread 'GMT 800 cab corners/rockers rust?'
- GM-Trucks.com forum thread 'Rusty rocker panels'
- Aftermarket 1999-2006 Chevy/GMC crew cab rear door rocker and cab corner repair panels (BodyShopPrice listing)
Chevrolet Silverado buyer questions
Is rust through at the rear cab corners and rocker panels (gmt800) serious on a Chevrolet Silverado?
We rate it major and very common on the Chevrolet Silverado. GMT800 Silverados and Sierras rust through at the lower rear corners of the cab and along the rocker panels under the doors, often while the rest of the body looks tidy. The rockers have drain paths that block with dirt, and the rear tyre throws water and road grit straight at the area ahead of the rear wheel. US-import trucks from salt states can be well advanced before any bubbling shows, and filler or stick-on rocker covers are a common way of hiding it. Repair means cutting out and welding in repair panels, and rot that reaches the cab mounts or door pillar makes it far more expensive.
How much does it cost to fix on a Chevrolet Silverado?
$800 to $4,500 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.
Which Chevrolet Silverado years are affected?
Our research records this fault on the 1999–2006 Chevrolet Silverado. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.
How do I check for it before I buy?
Open each door and look along the rocker sill and the bottom of the door frame with a phone torch for bubbling paint, rust holes or fresh filler. Look at the lower rear corners of the cab, just behind the doors and ahead of the rear wheels, and press gently with a thumb: soft or crunchy metal is rust through. Be suspicious of plastic or stainless rocker covers and thick fresh underseal, and ask what is under them. Lift the floor mats and feel the carpet for damp. If a workshop inspection is possible: on a hoist, have the inner rockers, cab mounts and cab floor checked from underneath, since outer panels are sometimes patched while the inner structure is rotten. Look here: Lower rear cab corners behind the doors, rocker panels under the doors, extended and crew cab rear door sills