The White star is the National Symbol and should be treated as such even though they were pretty much so phased out in the 1970s. The latest military markings manuals do allow for black stars on OD green trucks, however, in the 3" category. Those are usually verticle stars for bumpers and tailgates and such. And yes, according to my reading, the star, if placed on the hood of a military cargo truck or jeep, should be centered as much as possible.
Tanks with turrents having a horizontal star fall in a different category as the stars cannot be placed in center due to some obstructions provided by the build.
Point always goes forward toward the nose on a horizontal surface, point goes up on a vertical surface. You can also get the plastic high quality decals which seem to look better then most paint jobs I've ever seen, but paint is good too. Hard to mess up with the decals, easy to mess up a perfectly good OD paint job with a painted star. I've just recently had to remove some of my stars on a M-37 with a ring around it due to the fact they were not historically correct, though, today, my readings in military manuals indicate they were used indiscriminately by the military and it is permissible. The ring, broken or otherwise, came out in 1943 to indicate US for "invasion" vehicles above other military vehicles from foreign nations that would put the star in use. The M-37 was a post war era vehicle. Even though it could be used indiscriminately as was done in the military, I decided to remov the ring portion of the decal, and did so without damage to the paint underneath, so it looks like it was a good investment in buying high quality vinyl stars. Good luck with it.
