Leasing Companies

Larry's Truck Electric has to have an X in LTEX because it is a private firm (I believe my facts are straight). Let us say that railroad B is a class one with some surplus locomotives and the desire to lease them. If railroad B owned North America Leasing would the abbreviation be NAL since the leasing firm was owned by railroad B? Or would it have to be NALX despite railroad B owning it?

I think it would have an X since the company the railroad ''made up'' to lease the locomotives technically only exists on paper. I guess?