While the engine bay is empty, I decided to check the numbers. The engine number is stamped on the LH side of the block just above the oil pan, and is also stamped on the front LH chassis rail. The chassis rail has 59B094760 stamped on it, and so does the engine. This means that the engine is the original unit as fitted during production.
The other thing to check on the engine is the unit number. The engine should have a unit number of 96K as it is fitted with air conditioning. When I checked the unit number (at the rear of the block on the LH side), it was stamped with 96K. 96K is the unit number used for the base engine without air conditioning.
I next looked at the body build and options plate. Everything checks out except for the options.
Style 59 6339 = 4 Window Sedan De Ville OK
Trim 47 = Turquioise/Black OK
Paint 10 = Ebony Black OK
E = E Z Eye Glass. H = Heater. Y = 6 Way Power Seat
No Air Conditioning! This means the car was not fitted with factory air, so it must have been fitted at the dealer or after market. I am going to have to wait until I can have a look at the ventilation controls to see if a proper AC unit and switching is installed. Not sure if I should re-fit the air or leave it off.