This might put some light on it
The 150-160-180 hp Lycoming Engines
We will confine our discussion to the 150 hp and 160 hp 320 series and the 180 hp 360 series. These engines are assembled
largely from the same parts, and the differences are much more subtle than you might think. All of these engines use the same
crankcase casting. The basic casting is machined for three different type of engine mounts. The conical engine mount was the
first. This engine mounting system uses small rubber cones. The O-320-A and O-320-B engines use this mounting.
Next came the Dynafocal engine mount—now called the Type 1 Dynafocal mount. In this design the larger rubber isolators are
positioned at an angle of 30°. The intent was to “focus” the mounts just ahead of the center of gravity of the engine/propeller
combination. This mount proved to be very successful since it afforded a smoother ride. This Dynafocal mounting system is
the most commonly used system.
When Piper introduced the Twin Comanche, the aircraft had long extensions to the propeller hubs. This gave an exceptionally
clean cowling, but the center of gravity of the engine/propeller was moved ahead of the focal point of the Type 1 Dynafocal
mounts, so the angle was changed to 18° to compensate. This is known as the Type 2 Dynafocal and is used on the IO-320-B1A
engines. At the same time, larger “three inch” Lord isolators were developed.
So the crankcases are machined for one of the types of engine mounts—conical, Type 1 Dynafocal or Type 2 Dynafocal—and
they cannot be converted to any other type.