The most common red top is the 800U. The newer one is a bit smaller though. Basically, there is really only one size of Optima's. So either it first or you make it fit. I've got a older red top. Great battery. It fits in the YJ's tray and you can use the stock tie-down. Personally, unless you're going to be using the battery till it's almost drained, there is no real point in getting a yellow or blue. They are Deep-cycle and will take cycles of completely drained, better then the red tops. This would most likely mean your engine's dead and no one else has a winch. You'll probably want to upgrade the alternator before going with a dual setup. You might find you don't even need a dual setup. Oh and when you do setup a dual battermy, you really want them to be of the same age.
Also, you can wire them up two different ways. One's in serial while the other is in parallel. You can also have them wired so the second battery isn't used unless you switch to it. You have A, B, or A/B as your options.
As for the terminals, it is recommended not to attach the winch cables to the side terminals. (Although many do.) The reason not so is that the high amp draw (like when winching under a heavy load) will cause the terminal plates to heat up and melt. The side terminals use a strip of metal that connects to the top terminals.
In any case, the Optima's are good batteries. You'll notice how the started will sound different also. I believe the stock battery is a 400-500CCA while the Optima is a 800CCA
