When you add up the number of models available, in both the pickup and SUV categories, Toyota probably has more options available than any single nameplate, including Ford and Chevy. With a lineup that stretches from the compact Tacoma pickups to the almost-fullsize Tundra and SUVs in every size class-from the subcompact RAV4 all the way up to the fullsize Sequoia-Toyota offers a truck for virtually every possible buyer. And if you factor in three additional luxury SUVs marketed under the Lexus nameplate, you can make the argument that Toyota does indeed have the widest spread of models available.

Factor in nearly bulletproof drivetrains, TRD performance parts, exceptionally smooth V-8s for the Tundra, 4Runner, and Sequoia, along with legendary Toyota build quality, and it's a small wonder that Toyotas are so popular. Yet, when you think sport truck, rarely does Toyota come first to mind, although that's changing, especially in the two-wheel-drive prerunner classification.

Until recently, with the advent of fully integrated navigation systems available in almost all new Toyota vehicles, the one thing that you could depend on, application-wise, would be a big and flexible double-DIN opening in the dash. With older models, sans navigation systems, this will remain the case. If you have a late-model Toyota product, however, the height of the available opening has been reduced on many models and you'll probably elect to retain your full-featured (and expensive) head unit and concentrate on amplifier, speaker, and subwoofer upgrades. Given that almost every currently available amplifier has noise-free high-quality speaker-level inputs, adding power and upgraded speakers will be a snap.

Over the years, Toyota has used both 6-1/2-inch and 5x7-inch speakers in its truck applications. Before selecting any speakers, it's best to consult your local autosound specialist or a good online database. Quite possibly the best application database can be found on www.crutchfield.com, the mail-order home of Crutchfield. Sorted by make, model, and year, this is the definitive source for determining what fits almost any vehicle going back to 1969. For late-model vehicles, the site will have to most up-to-date information available.

A buyer's caveat: Most of the manufacturers of the top-brand equipment have taken a very hard line on unauthorized internet sales of their products, either in dedicated E-storefronts or on auction sites such as eBay. Several reserve the option of denying warranty service on units sold through non-authorized sales channels, especially if serial numbers have been removed or defaced. Some manufacturers have gone so far as to take legal action: Blaupunkt, Clarion, and Polk Audio, to name a few.

The bottom line is this: If you have any doubt about the retailer's factory authorization, call the factory. The addresses and phone numbers are easy to find on the web. The $15 dollars that you save buying a $500 amplifier now may come back to haunt you many times over should your component need service down the road. Buyer beware!