These are used to hold down the middle and rear bench in a VW bus. I am not sure about early split window models, but do know that these work in the bay windows. The unit is a combination of a t-bolt and hook-type bracket that clamps over the top of the seat rail to hold it in place. There is a small nipple on the underside of the bracket that goes into a hole on the top of the bench rails. The t-bolt slides into a notch in the floor of the bus. Once you have it slid in, you rotate it 90 degrees to help lock it in place. On a side note, the same t-bolts are used for the two rear most bolt down sections of the Westy foldout bed.Pics HERE.