OK I think I know what is going on. I looked at the rear end again, and as stated:
(1)(2) ----------------- (3)(4)
1 & 4 = turn/brake/tail
2 & 3 = reverse lights??
.... then I SHOULD use the dual filiment bulbs with the 2-wire sockets... because the sockets have those metal prongs on them --- which should be ground instead of using a wire for it, right? Then I will have 1 wire for the bright filiment, and 1 wire for the dull filiment = brake/tail? Then If I have the brake lights on, and hit the turn signals it will make the brake light that is on, flash? (If I wired it up correctly)