Soledad":1ntk5xlo said:
On the heads intake this will decode as September 23, 1961 or maybe the 28th only 5 days difference so close enough. Some of the old time Hot Rodder's would bolt on the 170 heads to a 200 block for a bit more compression.
On the exhaust manifold you have a January 6, 1967 this is quite close to the short blocks date code so I would say it's orginal to the engine.
The body's Vin code under the hood is more accurate as to production date because doors can be changed out. You should see a small cut out area on the drivers side fender were you can see stamped in Vin numbers on the apron. Yes the Vin numbers are also under the left side front fender apron in the Aprox same location on both sides and they should both match, there are also three other hidden Vin number locations on the body / chassis. In cases of collision damage sometimes these front apron parts are changed but there would be signs this has been done. I would need both of the full Vin numbers to be able to decode them. Yes that's quite the puzzle on the Vins, will take a little more detective work to solve that mystery.
Assuming that the engine maybe orginal to the car since it has a January build date this a mid year production car I would lean towards it being a 1967 model. But it's also possable the slightly newer engine was swapped into the Falcons chassis. From my time working on the Ford assembly line in the mid 1970's I know the aprox beginning of the new year model change over. The assembly plant was shut down the for two weeks at the end of June so that the new models could begin to be built in July through early September and be delivered to the Ford dealer show rooms for their mid September showings. So late end of the year 1966 build dates are actually a 1967 Ford year model even if they were sold in 1966 yet to confuse things even more in some states they would also register a car by the year it was first sold.
1966 year model Falcons were a new body style for the Falcon line and this body style was carried over with minor changes each year though into the 1970 models. Some of the changes from 1966 to the 1967 Falcon were a new grille, a large padded horn button on the steering wheel, and the side trims on Deluxe models, and the excellent Select Shift C4 trans (see links below for more info). In reality it doesn't matter all that much on the mechanical parts, chassis, body parts as there is great interchangeability over the years with a few exceptions. Also only if you were going to restore car to factory specs and needed to search for some year specific body and trim parts to match what your car was built with. Good luck
EditedExample of a 1966 Falcon
https://m.youtube.com/watch?v=lhJ7SlzryXQ
1967 Falcon Specs
https://www.falconclub.com/1967-2/
Excellent you have made some very good progress on your 1966 Falcon and finally zeroed in on the main cause of all your bogging troubles. You also won't be able to get the cruise air fuel ratio right (by changing the main jet) until that large vacuum leak is repaired first then that 200 engine is going to purr and get the great fuel economy that it was desgined to. Best of luck. 