The Hurricane is very well done. The rear leg slides down over a 6" long stub that is welded up from the frame in the trunk deck. Then the hoop legs are slid over two frame-welded 6" tall stubs mounted behind the driver's seat. Then the top of the rear leg is slid back up into its spot in the hoop and "wedged" into place and bolted. There are also bolts that hold the front hoop legs onto their mounts but they are really not needed because once the rear leg is wedged into place and bolted, the assembly is tri-pod wedged and cannot move up or down. I also have mounts for an identical passenger rollbar so I can someday be like Patrick. Well, sorta.....
I would not ride in much less own one of these cars without a frame-mounted rollbar.
EDIT>>>And I saw that rolled SPF in NE Houston from last year that was at Vintage Upgrades, in person. The twin rollbars and the way in which they were mounted made ALL the difference in the outcome of that rollover.