The body, base and bumper rest of the jack are painted a medium gray for Acadians and Beaumonts. I can take a pic of my un-restored one for you if you wish.
Mine is actually a Nova built in Canada. The parts you mentioned were painted black on mine. It looked to be original?? Any chance some were black and some were grey? This is an Oshawa built 66 Nova 2 door hardtop.
'64 Parisienne CS "barn find" - last on the road in '86 ... Owner Protection Plan booklet, original paint, original near-mint aqua interior, original aqua GM floor mats, original 283, factory posi, and original rust.