Different VR6 OBD1 manifolds, Left to Right: 2.8 VR6 manifold, early engraved type (rare) 2.8/2.9 VR6 manifold, early type 2.8/2.9 VR6 mainfold, later type Difference between 2.8 & 2.9 manifolds (later type) 2.8 on the left, 2.9 on the right. All of the manifolds pictured above are OBD1. The OBD2 2.8 manifold is similar to the 2.9 one in the above picture (marked "E"), except with changes to the throttle body mounting face and no ISV pipe flange (the flange right next to the TB mounting face). All OBD2 manifolds were the same design. An OBD1 manifold will not fit straight on an OBD2 en