Well, this is where the old saying "don't judge a book by it's cover" got it's meaning.
It depends on the build of the 97- some 97's are more like 96 and some are more like 98-up which is what you want. even then if they match, some engine sensors will be different, and, 99 is when the fuel injection system was changed from a return style with 2 fuel lines,( 98 down) to a returnless single line with an in tank pressure regulator.(99 -up)
The 97 probably has orange injectors, while the 99's will be off white-gray.
The systems will not interchange. while the older harness feels like it connects well the the newer injector, the connection is not made inside the plug. Orange injectors run on 30-45 psi fuel pressure, gray use 60+ psi fuel pressure.
Cam sensor -oil pressure sender, and coolant sensor connectors ( to name a few) will be different between harnesses.
Using the newer system will always be more efficient, however, the older system may not have the PATS issue to deal with. to use the new PCM all of the PATS stuff from newer truck will be needed to use the newer engine and make it start.
You can do it, but it means swapping everything from the new one to the old one so make sure you keep the new rolled one until all the bugs are worked out.
Your 97 will need an egr pipe on the passenger side exhaust manifold, like the 99 has. Otherwise, even the frame is a little different.
Interior parts will work fine,
