This is what I got from NPD. The kit def has clip-form nuts, not actual nuts. BUT they look exceptionally strong, so should do just fine. The washer is a cup style spring washer, so they ought to stay tight as well...
'68 400HO Coupe, 4 spd, 259 interior, Windward Blue. My other car's a Johnson 15 outboard on a '61 Starcraft rowboat... Just sayin'.