Extended cab rusting out on passenger side.

It happens because of improper ventilation if water gets into the inside of the corner of the cab. Notice the drivers side didn't do that? It is because of the third door and it ventilates properly.

mine has that problem too

Your best bet is to get it fixed with a new body panel and drill holes under the corner under the truck to allow ventilation. Spray a vehicle undercoating in the corner first so it doesn't rust from the inside out.

Check with your dealer. Most GM vehicles have a 7/75,000 or 10/100,000. mile rust perforation warranty( Outer body rust through). Actually rust is from accumulation of dust holding moisture and the oxygen in the water combining with the steel to form oxides(rust). I am an ASE Certified Master Collision Repair and Refinishing Tech. You also probably have a small water leak in that corner. Larry T. Potts

yeah it's a 2000 pickup with almost 300,000 km's on it, when i got it they said i had a 6 year rust warranty and the bubbling didn't start until about 3 months after the warranty expired.

You are out of the wrranty period, definitely. Check underneath the cab at the backside of the rocker panel/lower cab corner. There are probably holes that allowed water or other forms of moisture to get inside the cab corner. You also need to look for clogged drain holes that the factory builds in the seams of the lower panels, also look for missing plugs that are for the holes for draining the metal wash during building of the truck. These holes are about 1 inch in diameter, some may be oval shaped 1" wide and about 2" long. It does not make sense to repair the rust without fixing the water source. I don't know if you live in the "rust belt" or near salt water(oceans). This problem has occurred on a number of vehicles and previous care also affects the severity of the problem.

Rusting is natural in parts made of metal which is hard to stop if once started. Therefore only thing you can do is exercise some antirust methodologies like coat the cab corner with paint or wax. But still no one can guaranty the problem be shorted out permanently. Best thing is to remove cab corner and mount new one which you can equip from any of online retailer like http://www.iautobodyparts.com/chevrolet/suburban/1960/cab_corner/cab_corner-1-parts-0.html at reasonable price. I do recommend for replacement before getting other parts rusty.

cut that shit out!!!! any gear head or s10 guru will tell you, cut it out! tack weld in new replacement panels, or in my case im trying to use another s10 and cut it upp!!! luckly its a single cab, eight ft bed. lmao

power to all s10 followers.