I don't think the VIN gives any clues. Did all 1965 Rivi GS's come with 425's? Can you use the presence or absence of dual 4-barrel carbs? What is the secret? Craig
VIN gives no clues. 65's came with 401's and 425's. 65 Riv GS's all came with 425's. https://rivowners.org/features/Ev_Stats/productn.html Anyone can add or remove dual quads. You could even get dual quads on a non GS (454 built this way). If original motor still, it should be "LX" code 425 and VIN should match engine. If not original engine, it gets very difficult without factory paperwork. more reading here: https://rivowners.org/features/Ev_Stats/65gs/
