1965 Dodge Dart Charger

Dan! I checked the partscatalog and according to them they had the same straight type for 1964, 1965 and 1967. In 1967 they changed style to S shape. Check out the pictures.

Your parts book pics match my parts book pics, but the P/N remains the same (1828 352).

I don't know how you're seeing any hold-down in that old colour picture!

Found an old radiator cap in mint condition. Did they had the 16 psi or the 14psi

Both. 14-pound for standard cooling and without air conditioning. 16-pound for heavy-duty cooling and/or with air conditioning.