How many cars with original drivetrain are on this forum?
Mine is OEM, but not the original engine or transmission. Original engine had over 300,000 miles on it, rebuilt twice. The car has had two different engines in it since the car was restored. The first was a used one that came with it's transmission, that engine was replace a few years ago with a fresh rebuild. All were 273s in OEM trim.
Car has over 400,000 miles and counting so a change could happen down the road.
Alan