Brian,

Yup, actually the factory Tee (on my Ford) is light steel, and the plastic is inside the aftermarket brackets. I couldn't get myself to spend $200 for the aftermarket racks, and had my brother weld up some alum stands that bolt to the factory tee slot. The factory Tee is still very lightly attached to the roof though, it has just a few small (4mm?) fasteners holding it to the roof.

Dan

: If they're attached to plastic factory grooves, I agree. In my case, they're
: not necessary. That's what I meant about evaluating each rack installation
: before deciding what straps to use, or not use.