Although I owned a 1st gen a very long time ago, I am not nearly as familiar w/ them as 2nd gen's. If that was a 2nd gen, I would expect that rust to have originated from a leak in the cowl plenum. Once the seam sealer fails, I think the water and subsequent rust just follows the seams.Well, don't go looking for trouble because you're bound to find it. I guess I'll be metalworking this truck for a while. It's on both sides, not as bad on the left.