For my car I turned in the Out of State title to get my New title. Should have made a copy for records first. (Might save a SASE some day)
The GT per the VIN is a V8. Standard is the 180 HP 2-bbl; optional 235 HP 4-bbl.
Mine came with the Charger engine package and power Pak exhaust. When distinguishing between the Dart Charger and the factory option 4-bbl for the GT there may have been a different color resonator used. A similar discussion can be made Formula S vs. factory optioned Barracuda or Val. 4-bbl with Power Pak (1965). Parts manual may not be too clear for exhaust. I discussed exhaust briefly with Gib. Distinct factory sound(load); he used to taunt cops.
The door jam looks like it was metallic blue (not light yellow) when the replacement VIN applied?
You may have a valance cut out verifying 235 w/ power pak. For 1965 except for dart chargers the fenders were typically bare of emblems (no 273 4 Barrel) badges - (not absolute as with muffler/resonator info). I don't know if the 235 HP ever came with the turn down exhaust (no resonator)/ (no cut out) as a basic. My dad switched the 65 880 383 to the turn down with no problem. Don't remember the sound.
If you have (do find) a/ the build sheet(s) should have the VIN on it. Build sheets were typically printed at each station but not required to be placed or attached to car. They would build 1,000 plus cars a day, so build sheets are not absolute VIN verification (don't be bummed if they don't match/aren't there- mixed up/ thrown away etc.)
Not to drag this out but saw VIN Dart GT.. VIN #L4551618xx. LA built March 1965, (moparmuslecar). Your car possibly came 800-900 cars after that...?