Just a long shot, but check inside the trunk for a sticker.
My Ford dealer was able to find the code for my 2000 Expedition by using my VIN number. It seems that the same would apply to your situation.
On a 1995 Mercury Grand Marquis : firewall 4 - 8 3 - 7 2 - 6 1 - 5 front of vehicle
On a 1998 Mercury Grand Marquis : firewall 4 - 8 3 - 7 2 - 6 1 - 5 front of vehicle
There is no factory reset code for keyless entry on a 2000 Ford Excursion. To find the code, locate the module underneath the dashboard. You may need a borescope to look at the number.
The dealer can tell.
firewall 4 - 8 3 - 7 2 - 6 1 - 5 front of Mercury Grand Marquis
Passenger side rear
Passenger side second cylinder from the front.
take vin number to ford dealer and they should give them to you
firewall 4 - 8 3 - 7 2 - 6 1 - 5 front of Mercury Grand Marquis
The firing order for a 1997 Mercury Grand Marquis with a 4.6 liter engine is 1, 3, 7, 2, 6, 5, 4, 8. This means that number 1 fires first and number 8 fires last.
have a dealership lookup your VIN number remotes cost about $25 from the dealership