New heads on old bodies? (fenix)

[Jerb]

I have a l1p and l2p body and clicky, If I bought a new L2D CE would the head fit on my old bodies? what about the P series of lights?

 

[Talas]

I have an L1T and L2T and just got a P2D and the heads are NOT interchangeable. I was hoping to be able to upgrade my L2T. They must have changed the head size on the current L1D CE and L2D CE since these are supposed to be interchangeable with the P2D.