not an A body question but.....

We swapped seat belts from the originals to the new/used seats but we did plug them in with the two prong plug, I really think are problem here is the unused plug under the passenger seat, it was plugged in before the swap now there is nothing to plug it back in to? it comes up from the passenger floor, the only other thing would be if there is a plug we forgot under the seat but we looked and looked and couldn't see one, we seen a photo online of a 07 that had a cap plugged into the unused plug, I know some newer wire harnesses use resister terminator caps on the end of harnesses and wondered if that,s what we need to do?