[masraum]

So, I found on the US Millworks website that the "bolt" (part that screws into the car) is different from kit to kit to kit, not only due to possibly different threads, but also different lengths. They design each bolt to fit as closely as possible to be flush with the car. They also design the "bolt" to break if the car gets run into or runs into something so the car is less likely to be damaged. So I was able to order the correct bolt from them for my car. THe rest of the kit is all standard.

This is the difference between the 987 and 981 bolts. The 981 bolt is the long one. The threads on the 981 bolt are 18mm and 16mm long (and left hand). The threads on the 987 are 20mm and 18mm long (and right hand). The unthreaded shaft of the bolts are 4cm vs 10cm.