Ball and trunnion boot replacement

so let me get this straight, the rubber boot has to go over that big chunk of iron that covers the cross or am i missing something
No, you have to stuff the new boot inside and work it through without poking a hole in it! I you plan on reusing the clamps, carefully remove them. Cut the old boot off. Remove the end plate. Push the coupler housing in until you can remove the rollers. You might want to do that over a nice clean work bench so you don't lose any of the bearings or end caps. Once those parts are removed, you can start pushing the new boot through the housing. Make sure you get it going the right direction as you don't want to have to do it all over again if you get it in backwards! I don't envy you a bit!