1 point@ETI2K, since you asked about corrosion control...these are two good products to consider. Have used both for several years with good results. https://www.eastwood.com/internal-frame-coating-aerosol-black-14oz.html https://www.3m.com/3M/en_US/company-us/all-3m-products/~/Dynatron-Auto-Seam-Sealer-Caulk/?N=5002385+3293193911&rt=rud
1 pointPersonally I have stopped using weldthru primer, useless. Stitch weld, clean everything up well, 2k epoxy prime, continuous bead of seam sealer just the way OEM does then paint and undercoat. Good for another 40yrs.