5 point harness in a car w/o roll cage...How to do it?

Just installed a set of those Wescoperf 4- pointers in my '67 dart. Work nicely but IIHITDAOA, I would get retractable the 3- point type....You have to loosen the shoulder straps to reach anything or even look around...very similar to the racing type-4 point....albeit more comfortable. But still mucho safer than the original lap-only system. I used a big thick washer to anchor the floor mount..

(If I had it to do all over again)