'94 & '95 DI's were OBDI with one O2 sensor per cat (located in front of the cat). '96 through '99 DI's were OBDII with two O2 sensors per side (located in front and back of the cat).
If you are handy you could take the Y-pipe from an OBDI equipped truck and install a new bung for the back O2 sensor and use it on your '96. It would be easier, though, if you were going the other way, using and OBDII Y-pipe on an OBDI truck.