BEST way to tell is to pull a valve cover and read the top of the injectors.
'97's came with AA/AO unless it was bought new in CA, then it'd have AB Split Shot. Also, the '97 CA models had a dampner on the fuel pump, a big saucer/disk looking thing.
If you know for sure the truck was NOT bought new in CA, or if you don't have the dampner thingy, then you have AA/AO single shots.
UNLESS someone along the way messed with it.
I've seen over and over that some owner in the truck's history drops in a Single shot or 2 in a split shot truck, or mixes AB and AD thinking all the Splits are the same.
So after all that, like I started with, it's always best to pull a valve cover to know for sure.