Need help getting main caps off crank!!

Most mustang engines are Romeos, mine is, and they are jack screws. It's really wierd. The reason I couldn't figured out how to get them out is because the first main cap is different than the rest. The first one is a 7mm while the other 4 are 8mm. All I have is set of hex keys that has a 6mm and an 8mm. So i just tried the first cap last night and nothing fit. I tried the second main tonight with the 8mm and it worked. Same with the 3, 4, and 5 caps. I just need a 7mm for that first one now it seems. I can't get the 5th one out yet but the jack screws are open, just feels tight or there's something else I'm missing. I'll get a 7mm and give 1 a shot tomorrow. I need to get this block down to the machine shop asap. I want to get her back on the street for spring!!