It's a classic "hardtop sedan", with "hardtop" signifying that there's no B-pillar supporting the roof between the front and back doors. No B-pillar meant the door glass was frameless and when the windows were rolled down it was just one big opening from the A-pillar to the C-pillar.
The '68 had the 375bhp 4bbl 472 cubic inch V8 as the standard (and only) power plant option.