Ok guys, here is what we know so far. Differential oil boiled/burned and emits an intense stench. We replaced it with Royal Purple diff oils.
I'm also replacing the engine oil (I limped mode remember?) and at the same time installing an HKS oil cooler. Also changed the tranny oil just to be sure. The guy whom I bought the car from has been great and assisting me with everything I need.
I hope my car will be back to normal.
above: the real stinky oil after only 300 miles in the odo. I forgot to take a pick of the deformed drain plug bolt. It has a plastic covering and it was slightly deformed. (the plastic, not the metal parts). Just goes to show how hot the oil was. How could this be? We were going in a straight line. changing lanes was minimal.
I'll know tomorrow if the car is better. I'll prolly Dyno it so it can go 140 mph in a safe environment... see if the diffs boil again (at the same time, get a baseline dynapack reading). better to test it in a shop than in a highway in the middle of nowhere.