They did use a body sealant, which was very much like bathtub caulk. Cars are a very hostile environment though, plus the material has to be paintable, so hardware store sealants and cauljs aren't the way to go.
It may have varied over time, but mine appeared to have been a brushable seam sealant, applied from the inside once the doors had been adjusted and the bolts tightened down.
There are quite a few ready to go brushable seam sealants, but honestly, I've had terrible results with them. If they even behave through their curing cycle without splitting and peeling up like dried mud, they only last for a year or so, then fail in adhesion or disintegrate. They're probably geared towards quick body shop repairs. They smell atrocious for a long time too, (like as in weeks!!) as Toluene is the typical solvent.
I'd recommend looking for a 2-part seam sealer. These are often available in dual-cylinder self-mixing cartridges. There are numerous benefits; no long-lingering headache causing toxic chemical odors, fast cure times, great adhesion, long life, and fully paintable. 3M and Fusor both make reliable and readily available versions. A cartridge would probably run in the neighborhood of $40, which would do an entire vehicle.
-It's been such a LONG TIME... BlueShift>>
1981 Dodge Ram B250 Custom Sportsman Maxi Van
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