Just bought some 15x10 -43 offset fuel lethals and was just making sure of the lug nuts to get. Can some one tell me if I'm wrong lol. 1994 3.0 4wd pickup takes a 12x1.5 spline lug nut for these wheels right?

 

12mmx1.5 is the correct thread without knowing the wheels I have no clue of the style

I have wheels that use the short shank and washer some use the long shank and washer it depends on the wheel

 

Wyoming is right, the rim defines what shape lug nut (mounting surface, long, narrow, etc...) lug nuts are cheap, like $10 cheap. Go to Oreillys, or Autozone, or whatever is near you and just look at their selection, hell you can even buy a few different styles and see which one works best with your rim.