The E-Series and standard body series are not interchangeable.
The UExx will not fit nor function on a standard body such as a 6P.
SureFire makes two TailCaps into which you can plug a remote switch cable (SureFire offers two main types of remove switch cable), that will fit and function on the 6P.
XMxx (as shown in my photo above - it also has a push button pressure switch (that can be pressed for momentary on/off, or pressed hard for click on/off)
And here on an M2
Note that the black TailCap & tape pressure switch is the Classic version (it does not disconnect). I can example about it if you like...
UMxx that is a TailCap with a socket for the cable in the same way the UExx TailCap is.
This is a 650 WeaponLight modified with "M2" bezel, UM00 TailCap and SR05 Dual Function Tape Switch with Rail Clip (cable length 5")