I'm building a truck parts website right now. The end goal is for customers to select a year, make and model of truck. And then view the different products (categorized) available for that particular truck. And also the ability to shop by product brands within a product category. But I'm stumped, and looking for suggestions. I have products that fit vehicles going back to the 70's. Is there a way to make categories dependent as well? For example, let's say the user has a 1993 Toyota pickup. In that year Toyota had only one pickup. Later they made others, like the T100, Tacoma, and Tundra. So if the user selects 1993 and Toyota, only the models that existed in that year should show up or else a user could end up selecting a 1993 Toyota Tundra, which didn't even exist. Would a custom field for the year work better than a category? My initial thought was to use categories for make/model (ie. toyota/tundra) and then use either custom taxonomies or custom fields for the year. And then once I figure out how to organize products by vehicle fitment, I need to figure out the best way to organize the products themselves by brand and price groupings. An example would be Products: Air Filters, Exhaust Kits, Wheels, Lift Kits And in all of those categories I would have brand names as custom taxonomies. But they should be grouped by product type. For example under Air Filters, a user could search for K&N brand. But if someone is in the lift kits category I don't want them to see brands that don't even make products in that category. So I kind of need to group the brands by product type, does that make sense? Anyone have any suggestions or have you done something like this with automotive items or even cars/trucks themselves?