97 shouldn't need a VIN, but you're right about a lot of these companies not wanting to give out any info. The big difference between the sensors/injectors/etc. between OBDI and OBDII is the downstream O2 sensor. A trip to the local library for wiring diagrams will tell a greater story of any differences. The wiring and computers are certainly different, but there's no reason you can't make the 97 engine a 95, electrically.