How would you fix this one?
cant get to backside behind drip edge
How would you weld in patch?

 

What are we looking at? Can't figure it out from the pics you show.

 

This is some small rust holes behind drip edge on drivers door on a '74 f100.

here is another picture at a slightly different angle.

 

Sorry, I have no experience here. You might want to try one of the auto body forums on the net.

 

It looks like you have that blasted down to the metal - very good, much easier to repair. The holes don't look as bad as many I've seen on here and it appears that you have as much of the rust cleaned out as you can get too - which is also good.

1. Use Ospho or any other brand of Rust Inhibitor. Our local Lowes doesn't carry it anymore but you can easily find it on Amazon or I believe Lowes has their own brand. This is a liquid so spray it real well in the holes and on the surface. Follow the directions on the bottle.

2. Since it looks like a tight rail, I would use POR-15's Patch Seam Filler. It is expensive but this stuff works great and is very hard once it is cured. They say it can be applied right over rust but I like using the rust inhibitor just to be safe. This isn't the exact same one I used on our 1941 cab seam as back then POR had a sandable seam filler but I've had good luck with all of their products. I would fabricate several plastic scrap pieces to fit in your drip rail and body fill spreaders around. Eastwood actually has a nice 5 pack of various shapes for 3.99 a pack.
https://www.por15.com/POR-15-Patch-F...nd-Seam-Sealer

If you would really rather weld it, either search this forum for "drip" or wait for someone with this type of welding experience to come along.

Welcome to FTE and good luck with your project.

 

Thanks for the repy,
it looks like por 15 it is.
it has already been treated with ospho.
we have a local hardware store that keeps it in stock.