Has anyone tried to replace the C stick in the New 2ds XL with an analog stick. After doing some measurements it looks like a PSP 3000 analog stick is the right thickness and the cable looks right. Anyone that any thoughts on this?
By C stick, do you mean the circle pad, or the actual C stick nub?
The nub would require a very thin replacement to fit above the n2DS XL board and would need to function more as a trackpoint module, not like a dual potentiometer stick.
I think the circle pad would be possible:
I think you would need a bracket to hold the PSP3000 stick in place and a custom stick cap that's slimmer than the OEM one.
You might also need to remove the upper thumbstick screw hole to avoid interference with the L/ZL bracket.
Otherwise, it should fit in the spot in the n2DS XL board. Here's the footprint of just the PSP3000 stick, well within the bounds of the circle pad:
Electrically, the ribbon from the PSP3000 stick would probably fit in the connector on the n2DS XL board, they seem to both be 4 pin 0.5mm pitch with the same pinout.
You would want to confirm that the directions match up though.
I'd recommend getting a replacement shell and doing a dry fit to see if there's any interference if that's the route you want to go.
Best of luck!