Those are rear door patch panels...you can pick the up from DeWayne in TN.
He installs what he sells and offers discounts every now and again on parts.
http://nsanehotrodz.mybigcommerce.co...illar-rear-lt/
http://nsanehotrodz.mybigcommerce.com/patch-panels-4/
Disclaimer - if this piece needs replaced - there are likely more behind it that will need some work. Post up some pix and this group can tell you what you are in for.
It can all be fixed if you are up to it.