An easy way to tell could be to check if you can enter programming made
for the keyless entry remotes. My old '98 Windstar and my '03 F150 used
the same procedure. Put the key in the ignition and turn the key until
the all the dash lights come on and then turn off repeating this up to
8-10 times until you hear the doorlocks lock and then unlock. I believe
you can't take longer than three seconds between key turns otherwise you
have to start all over. Once the doorlocks cycle you can program up to
four keyless entry remotes.

If it does enter programming mode just shut the ignition off and after a
few seconds it will automatically enter normal mode. Then you go on Ebay
and buy up to four keyless entry remotes and save a ton of money.

I bought a used 1998 F150 XLT.   It has power door locks.  The previous
owners did not provide a keychain remote, nor do they know whether
there ever was one.

Before I go out and buy a set of remotes, how can I find out if my
truck is equiped for keyless entry?

Thanks,
AABob