Correct Tail Number for B-29 "Fifi"

There’s some discrepanacy over the correct tail number for the CAF B-29 “Fifi”.

I noticed many of her pictures on this site carry the number “NX529B” where others including my own list it as “N529B”.

There are several websites that list the plane as N529B without the X, but on some FLightAware pics, it is clearlyshown as NX529B.

Does anyone know the real deal with Fifi’s tail number? Is the X a special designation?

What would be the best way to list it in FA?

Thanks!

The correct registration is N529B; the X prefix indicates it is operated under the Experimental airworthiness certificate.

All about N-numbers: aahs-online.org/articles/N-number.php

Pat this was very helpful, thank you very much!