Wolfgang: Do you have the Signal Stat number of the base for the front directionals?
I think they might be the same diameter as the rear bee hives.
gn
Wait a minute - it looks like he's just swapping out the front lenses. The Porsche shallower lens (like I'm running) will fit onto the CMC directional base if you run a thicker gasket under the lens (between the lens and the base).
I got a sheet of closed-cell foam at Michael's (8-1/2" X 11") and made a few extra gasket washers for the lens and then just stacked them up (because my bulbs stuck out too far so I needed a taller lens) til they were thick enough to clear the bulb).
The base outer diameter of the CMC base is identical to a Porsche base and the lenses are interchangeable.
gn
This is hard to see, but those are shallow Porsche white front lenses on a CMC (Signal-Stat) base. I run amber-colored bulbs inside of them: