[Kos-Mos]

All internal parts will fit except the following:

-Anti-reversal latch
-Mechbox shell

You might want to change the motor at the same time you change the gear because ICS motors have a different angle of pinion and leads to a grinding noise if not changed, regardless of motor adjustment.

External parts can be hit or miss. The following can be fitted with little to no modifications, depending on brand and luck mostly:

-Any grip that is not ICS (require fitting all the time)
-Any stock that is not ICS (if your stock can fit over the ICS buffer tube, you can use it without any modifications)
-DBoy or JG brand front ends, and generally clone front ends. (Not a guaranty fit, but I have yet to find a clone front-end that required modifications)
-"TM" compatible front ends, reputable brands (require the receiver to be retreaded the right size, although I fitted a King Arms free float without issue on the same rifle an other King Arms front end would not fit)

Part that cannot be fitted:

-Trigger guard/bridge (it is longer than others)
-Receiver (both upper and lower, they are longer than normal and made different inside)