rusted suspension

[78k10383]

i have a 78 k10. im in the middle of a frame off restoration. on the rear of the truck there are two braces to go from frame rail to frame rail. there is one at the front leaf spring hanger and one at the rear of the frame. i went to a local chevrolet dealership and was told they no longer make these peices. i already grinded the rivets off and removed them because they were rusted out completly. Are there any companys out there that sell these parts. thanks