I'm having trouble correctly reinstalling the firewall pad retainer clips on my '66 Dearborn fastback. Even after fiddling with it most of the afternoon, I still don't have all of them locked in place. I'm having trouble pushing the pins hard enough to make them lock in. I got three out of the clips locked in, and getting them seated enough to lock took two people: one of us pushing on the head of the clip from inside the car, and one lightly gripping the protruding end of the clip on the firewall side with vise grips and pulling. Even then, it seemed to take way too much effort to install these things. How in the world did Ford do it originally? Is there something simple I'm overlooking or missing?
Also, after messing with the fastback at work today, I came home and looked at my '66 coupe. It's a mostly original car my dad bought with 22k miles in 1968, and I know the firewall pad has never been out of the car. The clips on the coupe didn't seem to protrude out as far through the firewall, but the clips were still solidly locked in place.
I'm using the clips pictured here, except mine are the originals.
Am I correct in thinking that the two "tangs" on the clips should protrude through to the engine side of the firewall to lock the clip in place?