At one time, the term SUV applied exclusively to body-on-frame vehicles, with early examples being essentially pickups with full-body sheetmetal and another row or two of seats. Most of them even rode on truck-based suspensions, right down to solid rear axles and leaf springs. Today, the landscape has changed drastically. The volume leaders are now compact unibody models, with the Honda CR-V and Ford Escape battling it out month-to-month for first place, both of them totaling more than 200,000 sales a year.

The former volume leader, the Ford Explorer, abandoned its truck roots starting with the 2011 model year, going to a unibody platform shared with the Ford Taurus. The Nissan Pathfinder followed suit for the 2013 model year, going to a stretched Murano platform. The originators of the genre are now the exceptions to the rule, but some stalwarts remain. Below are the remaining body-on-frame SUVs for the 2013 model year.

Cadillac Escalade/ESV

The Escalade actually dates back to the 1999, a hastily-cobbled response to Lincoln's 1998 introduction of the Expedition-based Navigator, but the one everyone remembers is the breakout 2002 model, with its bold, angular "Art and Science" grille. Although not a particularly high-volume model, the Escalade is a decent seller with a hefty profit margin, particularly the range-topping Platinum models that approach the six-figure mark. There was some speculation a few years ago that the Escalade could migrate to the unibody Lambda platform, but all indications are that the Escalade will continue on a body-on-frame truck chassis, with stronger, more efficient engines and bolder, chromier styling.

Chevrolet Tahoe/Suburban

These bread-and-butter fixtures of GM's SUV lineup will probably be some of the last models to still ride on a body-on-frame chassis. Despite the seemingly dated architecture, the GMT-900 models have always delivered surprisingly good fuel economy and maneuverability for their size and capabilities, two attributes appreciated by customers who's idea of recreation often includes watercraft, ski boats or campers, and all the associated equipment that comes with those pursuits. An all-new model will be following the 2014 Silverado by a few months.

Ford Expedition/EL

The Expedition is no longer the sales blockbuster it once was and the current model is starting to show its age, but don't throw in the towel on Ford's fullsize SUV yet. A powertrain update giving it the F-150's 5.0 V-8 or EcoBoost V-6 is practically a given, breathing new life into the platform. However, its long-term prospects are not quite as promising as the GM offerings, as Ford seems steadfastly committed to lightening and downsizing -- and more often than not, that means a unibody platform, as was the case with the Explorer.

GMC Yukon/XL

For what used to be GM's bespoke "truck" brand, even having the name in the official logo for a period, it's somewhat ironic that the Yukon line is GMC's only remaining SUV that's body-on-frame. Both the Acadia and Terrain are unibody, and the concepts shown in the last few years, most notably the Granite sub-compact, are getting smaller and more car-like. The Yukon and Suburban-sized Yukon XL are such staples of the lineup, we don't see them going unibody for the foreseeable future.

Infiniti QX56

Poised to become the QX80 for the 2014 model year, the second-generation QX56 departs from the Nissan Armada platform to ride on the global Patrol chassis. Although considerably more sophisticated and refined than its predecessor, the new model is still body-on-frame. However, the long-term prospects for Infiniti's luxo-lounge are shaky at best, with Infiniti head honcho Johann De Nysschen essentially saying the V-8 doesn't have much of a future in the Infiniti lineup. Whether that was specifically in reference to the car lineup or the entire brand, we don't know. If you like Infiniti's full-size luxury SUV, it might be advisable to buy one sooner rather than later.

Jeep Wrangler/Unlimited

Ever since the Willys MB, the definitive "Jeep" has always been body-on-frame, but Jeep has also been well-known for capable unibody off-roaders since the introduction of the XJ Cherokee in 1984. In fact, the Wrangler is the sole remaining body-on-frame model in the Jeep portfolio, for which thousands of off-road enthusiasts are thankful. Although quite adept off-road, the unibody Grand Cherokee requires quite a bit more modification in the form of rock rails and other bolt-ons to take the punishment the Wrangler is legendarily capable of. The Wrangler may not stay body-on-frame forever, but if the purists have any say, it probably will retain the configuration for at least another generation.

Lexus GX 460

Imagine a Toyota 4Runner with dressier styling, a more luxurious interior and a V-8 engine, and you essentially have the GX 460. As long as the 4Runner is around, the GX will probably be a part of the Lexus lineup as well, as the GX is sold in overseas markets as the Land Cruiser Prado and the GX and 4Runner share an assembly line in Japan. But only selling a modest 11,000 units in the U.S. market for 2012, compared to 48,000 4Runners and more than 95,000 of the popular Lexus RX crossover, it's unknown how much longer the GX will be part of the Lexus lineup.