I have a 2016 Fox 36 factory fork that uses the previous NA air cartridge needle system. I want to upgrade the fork to the newer NA2 system without changing to a new CSU.
Does anybody know if changing the topcap to a 2018 version (820-05-419-KIT) with the a new 150 airshaft assembly (820-02-537-KIT) will fit in the older crown steerer unit? The new airshaft piston bore is 1.287, I couldn’t find online the diameter of the older piston to compare them.
Any input is appreciated!

Thanks