I have specs for a 1991 Fuji Discovery, but it lists 400LX as OEM. 500LX was spec'd on the 1991 Fuji Suncrest. However, the 1992 Discovery is listed with 500LX, so I suspect that is what you have, FYI, the original price was $569 US.
You had me confused at first with the PX codes. I'm thinking to myself, " There's no way the second letter would be an X'. Then I realized that you meant the X in the generic sense, that it represented all the various month code possibilities.
I hope your trip goes well. Looks like I'll be anxiously awaiting your returm, but not just for the Fuji info.