On the 2A most bolts that were installed when the jeep was assembled at the factory were left unpainted. If you check out pictures of new jeeps in the ads you can usually see this. I do not remember what plating was used....The fenders, hood, grille, tailgate, windshield frame, and seats were all painted separately fron the jeep, and assembled...The WWII jeeps were "touched up" with OD green, but blending is not an issue with flat paint. I beleive the gas tanks were in the jeeps when they were sprayed, and became body color.
I don't see why the 3A would have been done much differently. I bet Bob W has the definitive answer on this tho.
Avoid the stainless fasteners in high strength areas, like suspension and steering, and also use antiseize as stainless is prone to galling the threads. A friend of mine who restores Advanced Design Chevrolet trucks for a living uses tons of stainless fasteners in his work. He buys boxes and when bought that way they aren't too spendy. One at a time out of the hardware store racks...way too rich for my blood.
