Don't attach much meaning to the "1973 vs 1974" issue. In the late '70s, CA enacted a mandatory vehicle inspection scheme that required a Smog check on all '74s & newer cars. So quite a few 'built-in-'73-but-sold-&-titled-in-'74' Panteras were re-registered with the CA DMV based on their actual '73 build dates. A DMV visual inspection was required to do this but no costly Smog inspection .
The Italian build date is on the riveted white plastic tag on the passenger door jamb (usually). Sometimes the window sticker had the actual import date from Italy on it, from which a '73 build-date could be inferred. Even Ford did this with 93 'U.S GTS' cars built in '73 but sold in '74. Some DMV employees would logically accept window sticker import dates, but others would not.
All this effort avoided the expensive and restrictive '74 CA Smog test, which also sometimes required one to buy several OEM parts required for '74 but not delivered on '73 builds. Back then, you could fail the Smog Test visually for missing emission parts even if the tailpipe sniffer test was passed.
It was all quite a mess and was not restricted to just Panteras. Other European built brands did this li'l real-build-date switch..This is about the only known instance of an earlier car being worth more than a later built car, since you had to go thru a CA DMV inspection to sell a car in CA back then.