67 Barracuda Vert Shoulder Belts Backseat

We are putting Sebring buckets in my daughter-in-law's 65 Mustang coupe for the three-point belts and more comfortable seats. I'm not sure about the BMW hardtop rear seatbelts, but my 2004 330Ci convertible has an odd arrangement and the shoulder anchor is in the middle, not on the sides, in the back seat.