Caged Nut for Door Pillar

[Pack's 10]

I noticed that the body shop the previous owner had install the driver side rocker panel did not put the bottom caged nut assembly back in on the pillar. I have done a search on here and have seen where Mar-K supposed to carry these. I have has zero luck finding them on their website (not very user friendly IMO). Any help would be appreciated. About to have to cut the kick panel open for rust repair (another short cut the body shop did), so this is the time to fix it.