new toy hauler and new truck

X2..lol! Well 3 main things have to come into play...I did a quick look at what makes the numbers come together. I'm not sold yet but here is what I learned today. The gearing for one, the transmission type and whether it is a 2 wheel or a 4x4. Cab and dual wheels seem to come in a little down the road...but I am wondering about spring packs and brake caliper sizes. Without seeing it I'm still skeptical. When you put together a build sheet and look at what changes when you change those parameters...You can either lose or gain 5000 pounds on average in the rating for the truck. So your telling me if I choose a better gear for mileage and lose in rating, that I am in reality getting the same truck running gear as the truck with a higher rating just with lower gears?? Same frame, same springs, same brakes? OK well transmission. An auto can tow more than a manual now these days? Some one educate us. OK 4x4 is a gray area but I would think a 4x4 suspension would be even tougher than a 2 wheel drive...Now I'm really confused. Sounds a lot like smoke and mirrors. What is the truth?