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Door trim removal

My rust was on my doors behind the trim under the body line. But you can see what I did to repair rust on my 04. Lots of grinding, sanding, welding, more grinding and sanding then prime and paint. I did it that way and only spent about $200.

Bed rust in the size you are talking. I would get some donor metal to weld in once you have all the rust removed. Get a grinder and make sure you grind it all out. Don't want to leave and seeds in there to start the process over again faster. Make sure anything that you do put in gets some good adhesion of something to stop rust once the repair is done. Lot of people here like POR-15.

 

About the only way to repair the holes in the bed would be welding in new material. Which I would think is acceptable since it is already all dinged up. I would also inspect it thoroughly for other spots that are rusting out and fix them as well. Then get a liner on it. I have Herculiner and for less than $100 you can have a good serviceable liner if you don't mind doing it yourself. The liner will prevent further corrosion from above which I assume was your problem. I wouldn't think you get enough snow, ice and salted roads to have caused the rust from the bottom. More likely from junk laying in the bed and holding moisture. The liner will solve that. But before you do any kind of liner (commerical or DIY) the bed will require some thorough prep work.