Convertible Rear Armrests
If your armrests snap in with tabs (spring metal) I would recommend that you have them built with a more flexible steel then what they use for the 67 to 69 dart rear convert arm rests.
I bought a set and one of the spring tabs snapped before it got into the slots (and yes I do know how to install them, I have had the OEM in and out many times)
This is OEM
They replaced the part, which was great. Trouble is the replacement did the same thing.
I ended up making my own clips from mild steel and haven't had any troubles.
My clips on ABCs part
My belief is the spring steel they are using is just too brittle, doesn't allow for enough flex before the metal is past it's elastic limit.
Just my 2 cents