[FC] What is an interlock on an FC?

[Merv Krull]

Hi again.... just noticed an item called an interlock that goes at the top and bottom of the rearward side door on my GB.

I see two shallow bolt holes near the top and bottom of the meeting edge of the door. I am quite sure nothing was there when I bought the van.

Are they necessary?

What do they do?

Can anyone send a picture off list?

toodles
Merv