blueguy
The Blue One
That makes me things. A lot of the older RWD cars have cross braces behind the backseat to provide structural support and prevent body flex and roll. That could be a possibility.
Not only older RWD cars...but my mid 80's Century had a single brace that was inbetween the trunk carpet and the backseat...
Likewise, I don't seeing strut tower braces doing much of anything compared to something way stronger like that.