Seems like most crossover toolboxes are similar in size, but there's many different designs. Some are deeper, some are taller above the rails, etc. Hard for anyone to tell you what size to get, when we dont know what all you're trying to put in it. I have a couple, one is a tracbox that slides front to back of the box on the rails for my ladder rack, very slick, but it could always be bigger. I also have a gullwing box that I had on my chevy, that box was really nice for storing small tools, as it was much easier to access from the side of the truck, whereas the other one pretty much requires you to jump up in the truck bed to get anything out of it. Lastly, I had some side-mount boxes on an older truck. Great for small tools and such, but not big enough for anything larger, but nice because I still had 4' between them in the truck bed for gear. All comes down to what you need and what you like I guess, just dont go cheap, there's alot of cheap garbage out there that wont hold up over time.