OBD2 conversion.
I have a 1995 (OBDI) Oldsmobile Delta 88 that I have converted to 1997 OBD2 (yes, I replaced the complete wiring harness) and had it programmed to be 1998 or 1999 Delta 88. I had to us a VIN that maintained the ABS, Theft Deterrent and fuel pump control (one speed). It took many months of investigation to do this.
First, how can I find out what VIN the ECM was flashed with, I gave the guy a list and he never told me which one he used.
Second, the engine was off a 2000 GM test auction, no ID was ever stamped on the block, but the transmission mentions that it has a 3.0X final ratio (I though it was 1 but I have to look up the picture of the plaque) which the ECM is not programmed for. It is programmed for a 2.X final ratio. This make the torque converter stay at almost full pressure shifts, yeah it jolts the dash ever time.
Third, how can I get the ECM flashed with the different ratio to stop the slamming into gear and keep the compatibility for all other components?
I suspect GM will have to make a special VIN program for this to work. But who and where can I get help?

it'll probly take a GM Tech tool to flash the ECM.
Unless you know someone with software that can hack the ECM.

Good Luck