253 and 255 are very different engines. 253 being SOHC and 255 being DOHC Turbo.
All USDM shortblocks since the mid '90s have the VIN stamped into a flat on the RH side of the block next to the bellhousing.
The black box on top of the thermostat housing is auxiliary sir valve. I don't know about thw digo dash, but the sensor for analog dash ones is one the roght side of tge thermostat housing. One wire connector in it. I would assume it is the same for digi dash too.
Edit: added a picture of it
I doubt a thrown rod would contaminate the oil system unless the issues started some time before the rod let go.
Youd want to know what signs of the rod letting go we’re there before the big event - knocking noises for example.
Cheers
Bennie
check separator plate on rear of engine for leakage - metal plate likely OK. IF it's plastic, replace with metal. (I think 96 would be metal - guys???)
Given the OPs name could the smell be caused by something unrelated to the car?
Until you find it you may want to carry a fire extinguisher with you and don't park it in the garage in case it goes up.
check cv boots? splashing that grease onto exhaust is a peculiar smell.
I once snagged a plastic shopping bag on the exhaust and it took a while for that to burn off and the smell to go away.